25 May, 2011
2 commits
-
When CONFIG_TMPFS=n mpol_to_str() is not declared in mempolicy.h.
However, in the NUMA case, the definition is always compiled.Since it is not strictly true that tmpfs is the only client, and since the
symbol was always lurking around anyways, export mpol_to_str()
unconditionally. Furthermore, this will allow us to move show_numa_map()
out of mempolicy.c and into the procfs subsystem.Signed-off-by: Stephen Wilson
Cc: KOSAKI Motohiro
Cc: Hugh Dickins
Cc: David Rientjes
Cc: Lee Schermerhorn
Cc: Alexey Dobriyan
Cc: Christoph Lameter
Cc: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In commit 48fce3429d ("mempolicies: unexport get_vma_policy()")
get_vma_policy() was marked static as all clients were local to
mempolicy.c.However, the decision to generate /proc/pid/numa_maps in the numa memory
policy code and outside the procfs subsystem introduces an artificial
interdependency between the two systems. Exporting get_vma_policy() once
again is the first step to clean up this interdependency.Signed-off-by: Stephen Wilson
Reviewed-by: KOSAKI Motohiro
Cc: Hugh Dickins
Cc: David Rientjes
Cc: Lee Schermerhorn
Cc: Alexey Dobriyan
Cc: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 Aug, 2010
1 commit
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The oom killer presently kills current whenever there is no more memory
free or reclaimable on its mempolicy's nodes. There is no guarantee that
current is a memory-hogging task or that killing it will free any
substantial amount of memory, however.In such situations, it is better to scan the tasklist for nodes that are
allowed to allocate on current's set of nodes and kill the task with the
highest badness() score. This ensures that the most memory-hogging task,
or the one configured by the user with /proc/pid/oom_adj, is always
selected in such scenarios.Signed-off-by: David Rientjes
Reviewed-by: KOSAKI Motohiro
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 May, 2010
1 commit
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Nick Piggin reported that the allocator may see an empty nodemask when
changing cpuset's mems[1]. It happens only on the kernel that do not do
atomic nodemask_t stores. (MAX_NUMNODES > BITS_PER_LONG)But I found that there is also a problem on the kernel that can do atomic
nodemask_t stores. The problem is that the allocator can't find a node to
alloc page when changing cpuset's mems though there is a lot of free
memory. The reason is like this:(mpol: mempolicy)
task1 task1's mpol task2
alloc page 1
alloc on node0? NO 1
1 change mems from 1 to 0
1 rebind task1's mpol
0-1 set new bits
0 clear disallowed bits
alloc on node1? NO 0
...
can't alloc page
goto oomI can use the attached program reproduce it by the following step:
# mkdir /dev/cpuset
# mount -t cpuset cpuset /dev/cpuset
# mkdir /dev/cpuset/1
# echo `cat /dev/cpuset/cpus` > /dev/cpuset/1/cpus
# echo `cat /dev/cpuset/mems` > /dev/cpuset/1/mems
# echo $$ > /dev/cpuset/1/tasks
# numactl --membind=`cat /dev/cpuset/mems` ./cpuset_mem_hog &
= max(nr_cpus - 1, 1)
# killall -s SIGUSR1 cpuset_mem_hog
# ./change_mems.shseveral hours later, oom will happen though there is a lot of free memory.
This patchset fixes this problem by expanding the nodes range first(set
newly allowed bits) and shrink it lazily(clear newly disallowed bits). So
we use a variable to tell the write-side task that read-side task is
reading nodemask, and the write-side task clears newly disallowed nodes
after read-side task ends the current memory allocation.This patch:
In order to fix no node to alloc memory, when we want to update mempolicy
and mems_allowed, we expand the set of nodes first (set all the newly
nodes) and shrink the set of nodes lazily(clean disallowed nodes), But the
mempolicy's rebind functions may breaks the expanding.So we restructure the mempolicy's rebind functions and split the rebind
work to two steps, just like the update of cpuset's mems: The 1st step:
expand the set of the mempolicy's nodes. The 2nd step: shrink the set of
the mempolicy's nodes. It is used when there is no real lock to protect
the mempolicy in the read-side. Otherwise we can do rebind work at once.In order to implement it, we define
enum mpol_rebind_step {
MPOL_REBIND_ONCE,
MPOL_REBIND_STEP1,
MPOL_REBIND_STEP2,
MPOL_REBIND_NSTEP,
};If the mempolicy needn't be updated by two steps, we can pass
MPOL_REBIND_ONCE to the rebind functions. Or we can pass
MPOL_REBIND_STEP1 to do the first step of the rebind work and pass
MPOL_REBIND_STEP2 to do the second step work.Besides that, it maybe long time between these two step and we have to
release the lock that protects mempolicy and mems_allowed. If we hold the
lock once again, we must check whether the current mempolicy is under the
rebinding (the first step has been done) or not, because the task may
alloc a new mempolicy when we don't hold the lock. So we defined the
following flag to identify it:#define MPOL_F_REBINDING (1 << 2)
The new functions will be used in the next patch.
Signed-off-by: Miao Xie
Cc: David Rientjes
Cc: Nick Piggin
Cc: Paul Menage
Cc: Lee Schermerhorn
Cc: Hugh Dickins
Cc: Ravikiran Thirumalai
Cc: KOSAKI Motohiro
Cc: Christoph Lameter
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Dec, 2009
1 commit
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This patch derives a "nodes_allowed" node mask from the numa mempolicy of
the task modifying the number of persistent huge pages to control the
allocation, freeing and adjusting of surplus huge pages when the pool page
count is modified via the new sysctl or sysfs attribute
"nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows:* For "default" [NULL] task mempolicy, a NULL nodemask_t pointer
is produced. This will cause the hugetlb subsystem to use
node_online_map as the "nodes_allowed". This preserves the
behavior before this patch.
* For "preferred" mempolicy, including explicit local allocation,
a nodemask with the single preferred node will be produced.
"local" policy will NOT track any internode migrations of the
task adjusting nr_hugepages.
* For "bind" and "interleave" policy, the mempolicy's nodemask
will be used.
* Other than to inform the construction of the nodes_allowed node
mask, the actual mempolicy mode is ignored. That is, all modes
behave like interleave over the resulting nodes_allowed mask
with no "fallback".See the updated documentation [next patch] for more information
about the implications of this patch.Examples:
Starting with:
Node 0 HugePages_Total: 0
Node 1 HugePages_Total: 0
Node 2 HugePages_Total: 0
Node 3 HugePages_Total: 0Default behavior [with or without this patch] balances persistent
hugepage allocation across nodes [with sufficient contiguous memory]:sysctl vm.nr_hugepages[_mempolicy]=32
yields:
Node 0 HugePages_Total: 8
Node 1 HugePages_Total: 8
Node 2 HugePages_Total: 8
Node 3 HugePages_Total: 8Of course, we only have nr_hugepages_mempolicy with the patch,
but with default mempolicy, nr_hugepages_mempolicy behaves the
same as nr_hugepages.Applying mempolicy--e.g., with numactl [using '-m' a.k.a.
'--membind' because it allows multiple nodes to be specified
and it's easy to type]--we can allocate huge pages on
individual nodes or sets of nodes. So, starting from the
condition above, with 8 huge pages per node, add 8 more to
node 2 using:numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40
This yields:
Node 0 HugePages_Total: 8
Node 1 HugePages_Total: 8
Node 2 HugePages_Total: 16
Node 3 HugePages_Total: 8The incremental 8 huge pages were restricted to node 2 by the
specified mempolicy.Similarly, we can use mempolicy to free persistent huge pages
from specified nodes:numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32
yields:
Node 0 HugePages_Total: 4
Node 1 HugePages_Total: 4
Node 2 HugePages_Total: 16
Node 3 HugePages_Total: 8The 8 huge pages freed were balanced over nodes 0 and 1.
[rientjes@google.com: accomodate reworked NODEMASK_ALLOC]
Signed-off-by: David Rientjes
Signed-off-by: Lee Schermerhorn
Acked-by: Mel Gorman
Reviewed-by: Andi Kleen
Cc: KAMEZAWA Hiroyuki
Cc: Randy Dunlap
Cc: Nishanth Aravamudan
Cc: Adam Litke
Cc: Andy Whitcroft
Cc: Eric Whitney
Cc: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Jul, 2008
1 commit
-
We'd like to support CONFIG_MEMORY_HOTREMOVE on s390, which depends on
CONFIG_MIGRATION. So far, CONFIG_MIGRATION is only available with NUMA
support.This patch makes CONFIG_MIGRATION selectable for architectures that define
ARCH_ENABLE_MEMORY_HOTREMOVE. When MIGRATION is enabled w/o NUMA, the
kernel won't compile because migrate_vmas() does not know about
vm_ops->migrate() and vma_migratable() does not know about policy_zone.
To fix this, those two functions can be restricted to '#ifdef CONFIG_NUMA'
because they are not being used w/o NUMA. vma_migratable() is moved over
from migrate.h to mempolicy.h.[kosaki.motohiro@jp.fujitsu.com: build fix]
Acked-by: Christoph Lameter
Signed-off-by: Gerald Schaefer
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Signed-off-by: KOSAKI Motorhiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
28 Apr, 2008
15 commits
-
This patch replaces the mempolicy mode, mode_flags, and nodemask in the
shmem_sb_info struct with a struct mempolicy pointer, initialized to NULL.
This removes dependency on the details of mempolicy from shmem.c and hugetlbfs
inode.c and simplifies the interfaces.mpol_parse_str() in mempolicy.c is changed to return, via a pointer to a
pointer arg, a struct mempolicy pointer on success. For MPOL_DEFAULT, the
returned pointer is NULL. Further, mpol_parse_str() now takes a 'no_context'
argument that causes the input nodemask to be stored in the w.user_nodemask of
the created mempolicy for use when the mempolicy is installed in a tmpfs inode
shared policy tree. At that time, any cpuset contextualization is applied to
the original input nodemask. This preserves the previous behavior where the
input nodemask was stored in the superblock. We can think of the returned
mempolicy as "context free".Because mpol_parse_str() is now calling mpol_new(), we can remove from
mpol_to_str() the semantic checks that mpol_new() already performs.Add 'no_context' parameter to mpol_to_str() to specify that it should format
the nodemask in w.user_nodemask for 'bind' and 'interleave' policies.Change mpol_shared_policy_init() to take a pointer to a "context free" struct
mempolicy and to create a new, "contextualized" mempolicy using the mode,
mode_flags and user_nodemask from the input mempolicy.Note: we know that the mempolicy passed to mpol_to_str() or
mpol_shared_policy_init() from a tmpfs superblock is "context free". This
is currently the only instance thereof. However, if we found more uses for
this concept, and introduced any ambiguity as to whether a mempolicy was
context free or not, we could add another internal mode flag to identify
context free mempolicies. Then, we could remove the 'no_context' argument
from mpol_to_str().Added shmem_get_sbmpol() to return a reference counted superblock mempolicy,
if one exists, to pass to mpol_shared_policy_init(). We must add the
reference under the sb stat_lock to prevent races with replacement of the mpol
by remount. This reference is removed in mpol_shared_policy_init().[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: another build fix]
[akpm@linux-foundation.org: yet another build fix]
Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mm/shmem.c currently contains functions to parse and display memory policy
strings for the tmpfs 'mpol' mount option. Move this to mm/mempolicy.c with
the rest of the mempolicy support. With subsequent patches, we'll be able to
remove knowledge of the details [mode, flags, policy, ...] completely from
shmem.c1) replace shmem_parse_mpol() in mm/shmem.c with mpol_parse_str() in
mm/mempolicy.c. Rework to use the policy_types[] array [used by
mpol_to_str()] to look up mode by name.2) use mpol_to_str() to format policy for shmem_show_mpol(). mpol_to_str()
expects a pointer to a struct mempolicy, so temporarily construct one.
This will be replaced with a reference to a struct mempolicy in the tmpfs
superblock in a subsequent patch.NOTE 1: I changed mpol_to_str() to use a colon ':' rather than an equal
sign '=' as the nodemask delimiter to match mpol_parse_str() and the
tmpfs/shmem mpol mount option formatting that now uses mpol_to_str(). This
is a user visible change to numa_maps, but then the addition of the mode
flags already changed the display. It makes sense to me to have the mounts
and numa_maps display the policy in the same format. However, if anyone
objects strongly, I can pass the desired nodemask delimeter as an arg to
mpol_to_str().Note 2: Like show_numa_map(), I don't check the return code from
mpol_to_str(). I do use a longer buffer than the one provided by
show_numa_map(), which seems to have sufficed so far.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now that we're using "preferred local" policy for system default, we need to
make this as fast as possible. Because of the variable size of the mempolicy
structure [based on size of nodemasks], the preferred_node may be in a
different cacheline from the mode. This can result in accessing an extra
cacheline in the normal case of system default policy. Suspect this is the
cause of an observed 2-3% slowdown in page fault testing relative to kernel
without this patch series.To alleviate this, use an internal mode flag, MPOL_F_LOCAL in the mempolicy
flags member which is guaranteed [?] to be in the same cacheline as the mode
itself.Verified that reworked mempolicy now performs slightly better on 25-rc8-mm1
for both anon and shmem segments with system default and vma [preferred local]
policy.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
After further discussion with Christoph Lameter, it has become clear that my
earlier attempts to clean up the mempolicy reference counting were a bit of
overkill in some areas, resulting in superflous ref/unref in what are usually
fast paths. In other areas, further inspection reveals that I botched the
unref for interleave policies.A separate patch, suitable for upstream/stable trees, fixes up the known
errors in the previous attempt to fix reference counting.This patch reworks the memory policy referencing counting and, one hopes,
simplifies the code. Maybe I'll get it right this time.See the update to the numa_memory_policy.txt document for a discussion of
memory policy reference counting that motivates this patch.Summary:
Lookup of mempolicy, based on (vma, address) need only add a reference for
shared policy, and we need only unref the policy when finished for shared
policies. So, this patch backs out all of the unneeded extra reference
counting added by my previous attempt. It then unrefs only shared policies
when we're finished with them, using the mpol_cond_put() [conditional put]
helper function introduced by this patch.Note that shmem_swapin() calls read_swap_cache_async() with a dummy vma
containing just the policy. read_swap_cache_async() can call alloc_page_vma()
multiple times, so we can't let alloc_page_vma() unref the shared policy in
this case. To avoid this, we make a copy of any non-null shared policy and
remove the MPOL_F_SHARED flag from the copy. This copy occurs before reading
a page [or multiple pages] from swap, so the overhead should not be an issue
here.I introduced a new static inline function "mpol_cond_copy()" to copy the
shared policy to an on-stack policy and remove the flags that would require a
conditional free. The current implementation of mpol_cond_copy() assumes that
the struct mempolicy contains no pointers to dynamically allocated structures
that must be duplicated or reference counted during copy.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
As part of yet another rework of mempolicy reference counting, we want to be
able to identify shared policies efficiently, because they have an extra ref
taken on lookup that needs to be removed when we're finished using the policy.Note: the extra ref is required because the policies are
shared between tasks/processes and can be changed/freed
by one task while another task is using them--e.g., for
page allocation.Building on David Rientjes mempolicy "mode flags" enhancement, this patch
indicates a "shared" policy by setting a new MPOL_F_SHARED flag in the flags
member of the struct mempolicy added by David. MPOL_F_SHARED, and any future
"internal mode flags" are reserved from bit zero up, as they will never be
passed in the upper bits of the mode argument of a mempolicy API.I set the MPOL_F_SHARED flag when the policy is installed in the shared policy
rb-tree. Don't need/want to clear the flag when removing from the tree as the
mempolicy is freed [unref'd] internally to the sp_delete() function. However,
a task could hold another reference on this mempolicy from a prior lookup. We
need the MPOL_F_SHARED flag to stay put so that any tasks holding a ref will
unref, eventually freeing, the mempolicy.A later patch in this series will introduce a function to conditionally unref
[mpol_free] a policy. The MPOL_F_SHARED flag is one reason [currently the
only reason] to unref/free a policy via the conditional free.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The terms 'policy' and 'mode' are both used in various places to describe the
semantics of the value stored in the 'policy' member of struct mempolicy.
Furthermore, the term 'policy' is used to refer to that member, to the entire
struct mempolicy and to the more abstract concept of the tuple consisting of a
"mode" and an optional node or set of nodes. Recently, we have added "mode
flags" that are passed in the upper bits of the 'mode' [or sometimes,
'policy'] member of the numa APIs.I'd like to resolve this confusion, which perhaps only exists in my mind, by
renaming the 'policy' member to 'mode' throughout, and fixing up the
Documentation. Man pages will be updated separately.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch renames mpol_copy() to mpol_dup() because, well, that's what it
does. Like, e.g., strdup() for strings, mpol_dup() takes a pointer to an
existing mempolicy, allocates a new one and copies the contents.In a later patch, I want to use the name mpol_copy() to copy the contents from
one mempolicy to another like, e.g., strcpy() does for strings.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This is a change that was requested some time ago by Mel Gorman. Makes sense
to me, so here it is.Note: I retain the name "mpol_free_shared_policy()" because it actually does
free the shared_policy, which is NOT a reference counted object. However, ...The mempolicy object[s] referenced by the shared_policy are reference counted,
so mpol_put() is used to release the reference held by the shared_policy. The
mempolicy might not be freed at this time, because some task attached to the
shared object associated with the shared policy may be in the process of
allocating a page based on the mempolicy. In that case, the task performing
the allocation will hold a reference on the mempolicy, obtained via
mpol_shared_policy_lookup(). The mempolicy will be freed when all tasks
holding such a reference have called mpol_put() for the mempolicy.Signed-off-by: Lee Schermerhorn
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Mel Gorman
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Removes forward definition of vm_area_struct in linux/mempolicy.h. We already
get it from the linux/slab.h -> linux/gfp.h include.Removes the unused mpol_set_vma_default() macro from linux/mempolicy.h.
Removes the extern definition of default_policy since it is only referenced,
as it should be, in mm/mempolicy.c.Cc: Paul Jackson
Cc: Christoph Lameter
Cc: Lee Schermerhorn
Cc: Andi Kleen
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Adds another optional mode flag, MPOL_F_RELATIVE_NODES, that specifies
nodemasks passed via set_mempolicy() or mbind() should be considered relative
to the current task's mems_allowed.When the mempolicy is created, the passed nodemask is folded and mapped onto
the current task's mems_allowed. For example, consider a task using
set_mempolicy() to pass MPOL_INTERLEAVE | MPOL_F_RELATIVE_NODES with a
nodemask of 1-3. If current's mems_allowed is 4-7, the effected nodemask is
5-7 (the second, third, and fourth node of mems_allowed).If the same task is attached to a cpuset, the mempolicy nodemask is rebound
each time the mems are changed. Some possible rebinds and results are:mems result
1-3 1-3
1-7 2-4
1,5-6 1,5-6
1,5-7 5-7Likewise, the zonelist built for MPOL_BIND acts on the set of zones assigned
to the resultant nodemask from the relative remap.In the MPOL_PREFERRED case, the preferred node is remapped from the currently
effected nodemask to the relative nodemask.This mempolicy mode flag was conceived of by Paul Jackson .
Cc: Paul Jackson
Cc: Christoph Lameter
Cc: Lee Schermerhorn
Cc: Andi Kleen
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add an optional mempolicy mode flag, MPOL_F_STATIC_NODES, that suppresses the
node remap when the policy is rebound.Adds another member to struct mempolicy, nodemask_t user_nodemask, as part of
a union with cpuset_mems_allowed:struct mempolicy {
...
union {
nodemask_t cpuset_mems_allowed;
nodemask_t user_nodemask;
} w;
}that stores the the nodemask that the user passed when he or she created the
mempolicy via set_mempolicy() or mbind(). When using MPOL_F_STATIC_NODES,
which is passed with any mempolicy mode, the user's passed nodemask
intersected with the VMA or task's allowed nodes is always used when
determining the preferred node, setting the MPOL_BIND zonelist, or creating
the interleave nodemask. This happens whenever the policy is rebound,
including when a task's cpuset assignment changes or the cpuset's mems are
changed.This creates an interesting side-effect in that it allows the mempolicy
"intent" to lie dormant and uneffected until it has access to the node(s) that
it desires. For example, if you currently ask for an interleaved policy over
a set of nodes that you do not have access to, the mempolicy is not created
and the task continues to use the previous policy. With this change, however,
it is possible to create the same mempolicy; it is only effected when access
to nodes in the nodemask is acquired.It is also possible to mount tmpfs with the static nodemask behavior when
specifying a node or nodemask. To do this, simply add "=static" immediately
following the mempolicy mode at mount time:mount -o remount mpol=interleave=static:1-3
Also removes mpol_check_policy() and folds its logic into mpol_new() since it
is now obsoleted. The unused vma_mpol_equal() is also removed.Cc: Paul Jackson
Cc: Christoph Lameter
Cc: Lee Schermerhorn
Cc: Andi Kleen
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
With the evolution of mempolicies, it is necessary to support mempolicy mode
flags that specify how the policy shall behave in certain circumstances. The
most immediate need for mode flag support is to suppress remapping the
nodemask of a policy at the time of rebind.Both the mempolicy mode and flags are passed by the user in the 'int policy'
formal of either the set_mempolicy() or mbind() syscall. A new constant,
MPOL_MODE_FLAGS, represents the union of legal optional flags that may be
passed as part of this int. Mempolicies that include illegal flags as part of
their policy are rejected as invalid.An additional member to struct mempolicy is added to support the mode flags:
struct mempolicy {
...
unsigned short policy;
unsigned short flags;
}The splitting of the 'int' actual passed by the user is done in
sys_set_mempolicy() and sys_mbind() for their respective syscalls. This is
done by intersecting the actual with MPOL_MODE_FLAGS, rejecting the syscall of
there are additional flags, and storing it in the new 'flags' member of struct
mempolicy. The intersection of the actual with ~MPOL_MODE_FLAGS is stored in
the 'policy' member of the struct and all current users of pol->policy remain
unchanged.The union of the policy mode and optional mode flags is passed back to the
user in get_mempolicy().This combination of mode and flags within the same actual does not break
userspace code that relies on get_mempolicy(&policy, ...) and eitherswitch (policy) {
case MPOL_BIND:
...
case MPOL_INTERLEAVE:
...
};statements or
if (policy == MPOL_INTERLEAVE) {
...
}statements. Such applications would need to use optional mode flags when
calling set_mempolicy() or mbind() for these previously implemented statements
to stop working. If an application does start using optional mode flags, it
will need to mask the optional flags off the policy in switch and conditional
statements that only test mode.An additional member is also added to struct shmem_sb_info to store the
optional mode flags.[hugh@veritas.com: shmem mpol: fix build warning]
Cc: Paul Jackson
Cc: Christoph Lameter
Cc: Lee Schermerhorn
Cc: Andi Kleen
Signed-off-by: David Rientjes
Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The mempolicy mode constants, MPOL_DEFAULT, MPOL_PREFERRED, MPOL_BIND, and
MPOL_INTERLEAVE, are better declared as part of an enum since they are
sequentially numbered and cannot be combined.The policy member of struct mempolicy is also converted from type short to
type unsigned short. A negative policy does not have any legitimate meaning,
so it is possible to change its type in preparation for adding optional mode
flags later.The equivalent member of struct shmem_sb_info is also changed from int to
unsigned short.For compatibility, the policy formal to get_mempolicy() remains as a pointer
to an int:int get_mempolicy(int *policy, unsigned long *nmask,
unsigned long maxnode, unsigned long addr,
unsigned long flags);although the only possible values is the range of type unsigned short.
Cc: Paul Jackson
Cc: Christoph Lameter
Cc: Lee Schermerhorn
Cc: Andi Kleen
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The MPOL_BIND policy creates a zonelist that is used for allocations
controlled by that mempolicy. As the per-node zonelist is already being
filtered based on a zone id, this patch adds a version of __alloc_pages() that
takes a nodemask for further filtering. This eliminates the need for
MPOL_BIND to create a custom zonelist.A positive benefit of this is that allocations using MPOL_BIND now use the
local node's distance-ordered zonelist instead of a custom node-id-ordered
zonelist. I.e., pages will be allocated from the closest allowed node with
available memory.[Lee.Schermerhorn@hp.com: Mempolicy: update stale documentation and comments]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask rework]
Signed-off-by: Mel Gorman
Acked-by: Christoph Lameter
Signed-off-by: Lee Schermerhorn
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Hugh Dickins
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Introduce a node_zonelist() helper function. It is used to lookup the
appropriate zonelist given a node and a GFP mask. The patch on its own is a
cleanup but it helps clarify parts of the two-zonelist-per-node patchset. If
necessary, it can be merged with the next patch in this set without problems.Reviewed-by: Christoph Lameter
Signed-off-by: Mel Gorman
Signed-off-by: Lee Schermerhorn
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Christoph Lameter
Cc: Hugh Dickins
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Oct, 2007
1 commit
-
Remove the filesystem support logic from the cpusets system and makes cpusets
a cgroup subsystemThe "cpuset" filesystem becomes a dummy filesystem; attempts to mount it get
passed through to the cgroup filesystem with the appropriate options to
emulate the old cpuset filesystem behaviour.Signed-off-by: Paul Menage
Cc: Serge E. Hallyn
Cc: "Eric W. Biederman"
Cc: Dave Hansen
Cc: Balbir Singh
Cc: Paul Jackson
Cc: Kirill Korotaev
Cc: Herbert Poetzl
Cc: Srivatsa Vaddagiri
Cc: Cedric Le Goater
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Oct, 2007
2 commits
-
This patch contains the following cleanups:
- every file should include the headers containing the prototypes for
its global functions
- make the follosing needlessly global functions static:
- migrate_to_node()
- do_mbind()
- sp_alloc()
- mpol_rebind_policy()[akpm@linux-foundation.org: fix uninitialised var warning]
Signed-off-by: Adrian Bunk
Acked-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Allow an application to query the memories allowed by its context.
Updated numa_memory_policy.txt to mention that applications can use this to
obtain allowed memories for constructing valid policies.TODO: update out-of-tree libnuma wrapper[s], or maybe add a new
wrapper--e.g., numa_get_mems_allowed() ?Also, update numa syscall man pages.
Tested with memtoy V>=0.13.
Signed-off-by: Lee Schermerhorn
Acked-by: Christoph Lameter
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Sep, 2007
1 commit
-
This patch proposes fixes to the reference counting of memory policy in the
page allocation paths and in show_numa_map(). Extracted from my "Memory
Policy Cleanups and Enhancements" series as stand-alone.Shared policy lookup [shmem] has always added a reference to the policy,
but this was never unrefed after page allocation or after formatting the
numa map data.Default system policy should not require additional ref counting, nor
should the current task's task policy. However, show_numa_map() calls
get_vma_policy() to examine what may be [likely is] another task's policy.
The latter case needs protection against freeing of the policy.This patch adds a reference count to a mempolicy returned by
get_vma_policy() when the policy is a vma policy or another task's
mempolicy. Again, shared policy is already reference counted on lookup. A
matching "unref" [__mpol_free()] is performed in alloc_page_vma() for
shared and vma policies, and in show_numa_map() for shared and another
task's mempolicy. We can call __mpol_free() directly, saving an admittedly
inexpensive inline NULL test, because we know we have a non-NULL policy.Handling policy ref counts for hugepages is a bit trickier.
huge_zonelist() returns a zone list that might come from a shared or vma
'BIND policy. In this case, we should hold the reference until after the
huge page allocation in dequeue_hugepage(). The patch modifies
huge_zonelist() to return a pointer to the mempolicy if it needs to be
unref'd after allocation.Kernel Build [16cpu, 32GB, ia64] - average of 10 runs:
w/o patch w/ refcount patch
Avg Std Devn Avg Std Devn
Real: 100.59 0.38 100.63 0.43
User: 1209.60 0.37 1209.91 0.31
System: 81.52 0.42 81.64 0.34Signed-off-by: Lee Schermerhorn
Acked-by: Andi Kleen
Cc: Christoph Lameter
Acked-by: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Aug, 2007
1 commit
-
The NUMA layer only supports NUMA policies for the highest zone. When
ZONE_MOVABLE is configured with kernelcore=, the the highest zone becomes
ZONE_MOVABLE. The result is that policies are only applied to allocations
like anonymous pages and page cache allocated from ZONE_MOVABLE when the
zone is used.This patch applies policies to the two highest zones when the highest zone
is ZONE_MOVABLE. As ZONE_MOVABLE consists of pages from the highest "real"
zone, it's always functionally equivalent.The patch has been tested on a variety of machines both NUMA and non-NUMA
covering x86, x86_64 and ppc64. No abnormal results were seen in
kernbench, tbench, dbench or hackbench. It passes regression tests from
the numactl package with and without kernelcore= once numactl tests are
patched to wait for vmstat counters to update.akpm: this is the nasty hack to fix NUMA mempolicies in the presence of
ZONE_MOVABLE and kernelcore= in 2.6.23. Christoph says "For .24 either merge
the mobility or get the other solution that Mel is working on. That solution
would only use a single zonelist per node and filter on the fly. That may
help performance and also help to make memory policies work better."Signed-off-by: Mel Gorman
Acked-by: Lee Schermerhorn
Tested-by: Lee Schermerhorn
Acked-by: Christoph Lameter
Cc: Andi Kleen
Cc: Paul Mundt
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Jul, 2007
1 commit
-
Huge pages are not movable so are not allocated from ZONE_MOVABLE. However,
as ZONE_MOVABLE will always have pages that can be migrated or reclaimed, it
can be used to satisfy hugepage allocations even when the system has been
running a long time. This allows an administrator to resize the hugepage pool
at runtime depending on the size of ZONE_MOVABLE.This patch adds a new sysctl called hugepages_treat_as_movable. When a
non-zero value is written to it, future allocations for the huge page pool
will use ZONE_MOVABLE. Despite huge pages being non-movable, we do not
introduce additional external fragmentation of note as huge pages are always
the largest contiguous block we care about.[akpm@linux-foundation.org: various fixes]
Signed-off-by: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Oct, 2006
1 commit
-
Mistyped an ifdef CONFIG_CPUSETS - fixed.
I doubt that anyone ever noticed. The impact of this typo was
that if someone:
1) was using MPOL_BIND to force off node allocations
2) while using cpusets to constrain memory placement
3) when that cpuset was migrating that jobs memory
4) while the tasks in that job were actively forking
then there was a rare chance that future allocations using
that MPOL_BIND policy would be node local, not off node.Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Sep, 2006
1 commit
-
After we have done this we can now do some typing cleanup.
The memory policy layer keeps a policy_zone that specifies
the zone that gets memory policies applied. This variable
can now be of type enum zone_type.The check_highest_zone function and the build_zonelists funnctionm must
then also take a enum zone_type parameter.Plus there are a number of loops over zones that also should use
zone_type.We run into some troubles at some points with functions that need a
zone_type variable to become -1. Fix that up.[pj@sgi.com: fix set_mempolicy() crash]
Signed-off-by: Christoph Lameter
Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
21 Jun, 2006
1 commit
-
* git://git.infradead.org/hdrcleanup-2.6: (63 commits)
[S390] __FD_foo definitions.
Switch to __s32 types in joystick.h instead of C99 types for consistency.
Add to headers included for userspace in
Move inclusion of out of user scope in asm-x86_64/mtrr.h
Remove struct fddi_statistics from user view in
Move user-visible parts of drivers/s390/crypto/z90crypt.h to include/asm-s390
Revert include/media changes: Mauro says those ioctls are only used in-kernel(!)
Include and use __uXX types in
Use __uXX types in , include too
Remove private struct dx_hash_info from public view in
Include and use __uXX types in
Use __uXX types in for struct divert_blk et al.
Use __u32 for elf_addr_t in , not u32. It's user-visible.
Remove PPP_FCS from user view in , remove __P mess entirely
Use __uXX types in user-visible structures in
Don't use 'u32' in user-visible struct ip_conntrack_old_tuple.
Use __uXX types for S390 DASD volume label definitions which are user-visible
S390 BIODASDREADCMB ioctl should use __u64 not u64 type.
Remove unneeded inclusion of from
Fix private integer types used in V4L2 ioctls.
...Manually resolve conflict in include/linux/mtd/physmap.h
09 Jun, 2006
1 commit
-
From: Ralf Baechle
uses struct mm_struct and relies on a definition or
declaration somehow magically being dragged in which may result in a
build:[...]
CC mm/mempolicy.o
In file included from mm/mempolicy.c:69:
include/linux/mempolicy.h:150: warning: âstruct mm_structâ declared inside parameter list
include/linux/mempolicy.h:150: warning: its scope is only this definition or declaration, which is probably not what you want
include/linux/mempolicy.h:175: warning: âstruct mm_structâ declared inside parameter list
mm/mempolicy.c:622: error: conflicting types for âdo_migrate_pagesâ
include/linux/mempolicy.h:175: error: previous declaration of âdo_migrate_pagesâ was here
mm/mempolicy.c:1661: error: conflicting types for âmpol_rebind_mmâ
include/linux/mempolicy.h:150: error: previous declaration of âmpol_rebind_mmâ was here
make[1]: *** [mm/mempolicy.o] Error 1
make: *** [mm] Error 2
[ralf@denk linux-ip35]$Including is a step into direction of include hell so
fixed by adding a forward declaration of struct mm_struct instead.Signed-off-by: Ralf Baechle
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Apr, 2006
1 commit
-
Signed-off-by: David Woodhouse
24 Mar, 2006
1 commit
-
The hooks in the slab cache allocator code path for support of NUMA
mempolicies and cpuset memory spreading are in an important code path. Many
systems will use neither feature.This patch optimizes those hooks down to a single check of some bits in the
current tasks task_struct flags. For non NUMA systems, this hook and related
code is already ifdef'd out.The optimization is done by using another task flag, set if the task is using
a non-default NUMA mempolicy. Taking this flag bit along with the
PF_SPREAD_PAGE and PF_SPREAD_SLAB flag bits added earlier in this 'cpuset
memory spreading' patch set, one can check for the combination of any of these
special case memory placement mechanisms with a single test of the current
tasks task_struct flags.This patch also tightens up the code, to save a few bytes of kernel text
space, and moves some of it out of line. Due to the nested inlines called
from multiple places, we were ending up with three copies of this code, which
once we get off the main code path (for local node allocation) seems a bit
wasteful of instruction memory.Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Jan, 2006
1 commit
-
This patch fixes a regression in 2.6.14 against 2.6.13 that causes an
imbalance in memory allocation during bootup.The slab allocator in 2.6.13 is not numa aware and simply calls
alloc_pages(). This means that memory policies may control the behavior of
alloc_pages(). During bootup the memory policy is set to MPOL_INTERLEAVE
resulting in the spreading out of allocations during bootup over all
available nodes. The slab allocator in 2.6.13 has only a single list of
slab pages. As a result the per cpu slab cache and the spinlock controlled
page lists may contain slab entries from off node memory. The slab
allocator in 2.6.13 makes no effort to discern the locality of an entry on
its lists.The NUMA aware slab allocator in 2.6.14 controls locality of the slab pages
explicitly by calling alloc_pages_node(). The NUMA slab allocator manages
slab entries by having lists of available slab pages for each node. The
per cpu slab cache can only contain slab entries associated with the node
local to the processor. This guarantees that the default allocation mode
of the slab allocator always assigns local memory if available.Setting MPOL_INTERLEAVE as a default policy during bootup has no effect
anymore. In 2.6.14 all node unspecific slab allocations are performed on
the boot processor. This means that most of key data structures are
allocated on one node. Most processors will have to refer to these
structures making the boot node a potential bottleneck. This may reduce
performance and cause unnecessary memory pressure on the boot node.This patch implements NUMA policies in the slab layer. There is the need
of explicit application of NUMA memory policies by the slab allcator itself
since the NUMA slab allocator does no longer let the page_allocator control
locality.The check for policies is made directly at the beginning of __cache_alloc
using current->mempolicy. The memory policy is already frequently checked
by the page allocator (alloc_page_vma() and alloc_page_current()). So it
is highly likely that the cacheline is present. For MPOL_INTERLEAVE
kmalloc() will spread out each request to one node after another so that an
equal distribution of allocations can be obtained during bootup.It is not possible to push the policy check to lower layers of the NUMA
slab allocator since the per cpu caches are now only containing slab
entries from the current node. If the policy says that the local node is
not to be preferred or forbidden then there is no point in checking the
slab cache or local list of slab pages. The allocation better be directed
immediately to the lists containing slab entries for the allowed set of
nodes.This way of applying policy also fixes another strange behavior in 2.6.13.
alloc_pages() is controlled by the memory allocation policy of the current
process. It could therefore be that one process is running with
MPOL_INTERLEAVE and would f.e. obtain a new page following that policy
since no slab entries are in the lists anymore. A page can typically be
used for multiple slab entries but lets say that the current process is
only using one. The other entries are then added to the slab lists. These
are now non local entries in the slab lists despite of the possible
availability of local pages that would provide faster access and increase
the performance of the application.Another process without MPOL_INTERLEAVE may now run and expect a local slab
entry from kmalloc(). However, there are still these free slab entries
from the off node page obtained from the other process via MPOL_INTERLEAVE
in the cache. The process will then get an off node slab entry although
other slab entries may be available that are local to that process. This
means that the policy if one process may contaminate the locality of the
slab caches for other processes.This patch in effect insures that a per process policy is followed for the
allocation of slab entries and that there cannot be a memory policy
influence from one process to another. A process with default policy will
always get a local slab entry if one is available. And the process using
memory policies will get its memory arranged as requested. Off-node slab
allocation will require the use of spinlocks and will make the use of per
cpu caches not possible. A process using memory policies to redirect
allocations offnode will have to cope with additional lock overhead in
addition to the latency added by the need to access a remote slab entry.Changes V1->V2
- Remove #ifdef CONFIG_NUMA by moving forward declaration into
prior #ifdef CONFIG_NUMA section.- Give the function determining the node number to use a saner
name.Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Jan, 2006
1 commit
-
Anything that writes into a tmpfs filesystem is liable to disproportionately
decrease the available memory on a particular node. Since there's no telling
what sort of application (e.g. dd/cp/cat) might be dropping large files
there, this lets the admin choose the appropriate default behavior for their
site's situation.Introduce a tmpfs mount option which allows specifying a memory policy and
a second option to specify the nodelist for that policy. With the default
policy, tmpfs will behave as it does today. This patch adds support for
preferred, bind, and interleave policies.The default policy will cause pages to be added to tmpfs files on the node
which is doing the writing. Some jobs expect a single process to create
and manage the tmpfs files. This results in a node which has a
significantly reduced number of free pages.With this patch, the administrator can specify the policy and nodes for
that policy where they would prefer allocations.This patch was originally written by Brent Casavant and Hugh Dickins. I
added support for the bind and preferred policies and the mpol_nodelist
mount option.Signed-off-by: Brent Casavant
Signed-off-by: Hugh Dickins
Signed-off-by: Robin Holt
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Jan, 2006
5 commits
-
Fix more of longstanding bug in cpuset/mempolicy interaction.
NUMA mempolicies (mm/mempolicy.c) are constrained by the current tasks cpuset
to just the Memory Nodes allowed by that cpuset. The kernel maintains
internal state for each mempolicy, tracking what nodes are used for the
MPOL_INTERLEAVE, MPOL_BIND or MPOL_PREFERRED policies.When a tasks cpuset memory placement changes, whether because the cpuset
changed, or because the task was attached to a different cpuset, then the
tasks mempolicies have to be rebound to the new cpuset placement, so as to
preserve the cpuset-relative numbering of the nodes in that policy.An earlier fix handled such mempolicy rebinding for mempolicies attached to a
task.This fix rebinds mempolicies attached to vma's (address ranges in a tasks
address space.) Due to the need to hold the task->mm->mmap_sem semaphore while
updating vma's, the rebinding of vma mempolicies has to be done when the
cpuset memory placement is changed, at which time mmap_sem can be safely
acquired. The tasks mempolicy is rebound later, when the task next attempts
to allocate memory and notices that its task->cpuset_mems_generation is
out-of-date with its cpusets mems_generation.Because walking the tasklist to find all tasks attached to a changing cpuset
requires holding tasklist_lock, a spinlock, one cannot update the vma's of the
affected tasks while doing the tasklist scan. In general, one cannot acquire
a semaphore (which can sleep) while already holding a spinlock (such as
tasklist_lock). So a list of mm references has to be built up during the
tasklist scan, then the tasklist lock dropped, then for each mm, its mmap_sem
acquired, and the vma's in that mm rebound.Once the tasklist lock is dropped, affected tasks may fork new tasks, before
their mm's are rebound. A kernel global 'cpuset_being_rebound' is set to
point to the cpuset being rebound (there can only be one; cpuset modifications
are done under a global 'manage_sem' semaphore), and the mpol_copy code that
is used to copy a tasks mempolicies during fork catches such forking tasks,
and ensures their children are also rebound.When a task is moved to a different cpuset, it is easier, as there is only one
task involved. It's mm->vma's are scanned, using the same
mpol_rebind_policy() as used above.It may happen that both the mpol_copy hook and the update done via the
tasklist scan update the same mm twice. This is ok, as the mempolicies of
each vma in an mm keep track of what mems_allowed they are relative to, and
safely no-op a second request to rebind to the same nodes.Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Cleanup, reorganize and make more robust the mempolicy.c code to rebind
mempolicies relative to the containing cpuset after a tasks memory placement
changes.The real motivator for this cleanup patch is to lay more groundwork for the
upcoming patch to correctly rebind NUMA mempolicies that are attached to vma's
after the containing cpuset memory placement changes.NUMA mempolicies are constrained by the cpuset their task is a member of.
When either (1) a task is moved to a different cpuset, or (2) the 'mems'
mems_allowed of a cpuset is changed, then the NUMA mempolicies have embedded
node numbers (for MPOL_BIND, MPOL_INTERLEAVE and MPOL_PREFERRED) that need to
be recalculated, relative to their new cpuset placement.The old code used an unreliable method of determining what was the old
mems_allowed constraining the mempolicy. It just looked at the tasks
mems_allowed value. This sort of worked with the present code, that just
rebinds the -task- mempolicy, and leaves any -vma- mempolicies broken,
referring to the old nodes. But in an upcoming patch, the vma mempolicies
will be rebound as well. Then the order in which the various task and vma
mempolicies are updated will no longer be deterministic, and one can no longer
count on the task->mems_allowed holding the old value for as long as needed.
It's not even clear if the current code was guaranteed to work reliably for
task mempolicies.So I added a mems_allowed field to each mempolicy, stating exactly what
mems_allowed the policy is relative to, and updated synchronously and reliably
anytime that the mempolicy is rebound.Also removed a useless wrapper routine, numa_policy_rebind(), and had its
caller, cpuset_update_task_memory_state(), call directly to the rewritten
policy_rebind() routine, and made that rebind routine extern instead of
static, and added a "mpol_" prefix to its name, making it
mpol_rebind_policy().Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Since the numa_maps functionality is now in mempolicy.c we no longer need to
export get_vma_policy().Signed-off-by: Christoph Lameter
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add a boolean "memory_migrate" to each cpuset, represented by a file
containing "0" or "1" in each directory below /dev/cpuset.It defaults to false (file contains "0"). It can be set true by writing
"1" to the file.If true, then anytime that a task is attached to the cpuset so marked, the
pages of that task will be moved to that cpuset, preserving, to the extent
practical, the cpuset-relative placement of the pages.Also anytime that a cpuset so marked has its memory placement changed (by
writing to its "mems" file), the tasks in that cpuset will have their pages
moved to the cpusets new nodes, preserving, to the extent practical, the
cpuset-relative placement of the moved pages.Signed-off-by: Paul Jackson
Cc: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sys_migrate_pages implementation using swap based page migration
This is the original API proposed by Ray Bryant in his posts during the first
half of 2005 on linux-mm@kvack.org and linux-kernel@vger.kernel.org.The intent of sys_migrate is to migrate memory of a process. A process may
have migrated to another node. Memory was allocated optimally for the prior
context. sys_migrate_pages allows to shift the memory to the new node.sys_migrate_pages is also useful if the processes available memory nodes have
changed through cpuset operations to manually move the processes memory. Paul
Jackson is working on an automated mechanism that will allow an automatic
migration if the cpuset of a process is changed. However, a user may decide
to manually control the migration.This implementation is put into the policy layer since it uses concepts and
functions that are also needed for mbind and friends. The patch also provides
a do_migrate_pages function that may be useful for cpusets to automatically
move memory. sys_migrate_pages does not modify policies in contrast to Ray's
implementation.The current code here is based on the swap based page migration capability and
thus is not able to preserve the physical layout relative to it containing
nodeset (which may be a cpuset). When direct page migration becomes available
then the implementation needs to be changed to do a isomorphic move of pages
between different nodesets. The current implementation simply evicts all
pages in source nodeset that are not in the target nodeset.Patch supports ia64, i386 and x86_64.
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds