26 Mar, 2016
1 commit
-
Add KASAN hooks to SLAB allocator.
This patch is based on the "mm: kasan: unified support for SLUB and SLAB
allocators" patch originally prepared by Dmitry Chernenkov.Signed-off-by: Alexander Potapenko
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Cc: Andrey Konovalov
Cc: Dmitry Vyukov
Cc: Andrey Ryabinin
Cc: Steven Rostedt
Cc: Konstantin Serebryany
Cc: Dmitry Chernenkov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Mar, 2016
1 commit
-
SLUB already has a redzone debugging feature. But it is only positioned
at the end of object (aka right redzone) so it cannot catch left oob.
Although current object's right redzone acts as left redzone of next
object, first object in a slab cannot take advantage of this effect.
This patch explicitly adds a left red zone to each object to detect left
oob more precisely.Background:
Someone complained to me that left OOB doesn't catch even if KASAN is
enabled which does page allocation debugging. That page is out of our
control so it would be allocated when left OOB happens and, in this
case, we can't find OOB. Moreover, SLUB debugging feature can be
enabled without page allocator debugging and, in this case, we will miss
that OOB.Before trying to implement, I expected that changes would be too
complex, but, it doesn't look that complex to me now. Almost changes
are applied to debug specific functions so I feel okay.Signed-off-by: Joonsoo Kim
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
21 Jan, 2016
1 commit
-
The cgroup2 memory controller will account important in-kernel memory
consumers per default. Move all necessary components to CONFIG_MEMCG.Signed-off-by: Johannes Weiner
Acked-by: Vladimir Davydov
Cc: Michal Hocko
Cc: Arnd Bergmann
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Feb, 2015
2 commits
-
Remove static and add function declarations to linux/slub_def.h so it
could be used by kernel address sanitizer.Signed-off-by: Andrey Ryabinin
Cc: Dmitry Vyukov
Cc: Konstantin Serebryany
Cc: Dmitry Chernenkov
Signed-off-by: Andrey Konovalov
Cc: Yuri Gribov
Cc: Konstantin Khlebnikov
Cc: Sasha Levin
Cc: Christoph Lameter
Cc: Joonsoo Kim
Cc: Dave Hansen
Cc: Andi Kleen
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
virt_to_obj takes kmem_cache address, address of slab page, address x
pointing somewhere inside slab object, and returns address of the
beginning of object.Signed-off-by: Andrey Ryabinin
Acked-by: Christoph Lameter
Cc: Dmitry Vyukov
Cc: Konstantin Serebryany
Cc: Dmitry Chernenkov
Signed-off-by: Andrey Konovalov
Cc: Yuri Gribov
Cc: Konstantin Khlebnikov
Cc: Sasha Levin
Cc: Christoph Lameter
Cc: Joonsoo Kim
Cc: Dave Hansen
Cc: Andi Kleen
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Cc: Pekka Enberg
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Feb, 2015
1 commit
-
Currently, kmem_cache stores a pointer to struct memcg_cache_params
instead of embedding it. The rationale is to save memory when kmem
accounting is disabled. However, the memcg_cache_params has shrivelled
drastically since it was first introduced:* Initially:
struct memcg_cache_params {
bool is_root_cache;
union {
struct kmem_cache *memcg_caches[0];
struct {
struct mem_cgroup *memcg;
struct list_head list;
struct kmem_cache *root_cache;
bool dead;
atomic_t nr_pages;
struct work_struct destroy;
};
};
};* Now:
struct memcg_cache_params {
bool is_root_cache;
union {
struct {
struct rcu_head rcu_head;
struct kmem_cache *memcg_caches[0];
};
struct {
struct mem_cgroup *memcg;
struct kmem_cache *root_cache;
};
};
};So the memory saving does not seem to be a clear win anymore.
OTOH, keeping a pointer to memcg_cache_params struct instead of embedding
it results in touching one more cache line on kmem alloc/free hot paths.
Besides, it makes linking kmem caches in a list chained by a field of
struct memcg_cache_params really painful due to a level of indirection,
while I want to make them linked in the following patch. That said, let
us embed it.Signed-off-by: Vladimir Davydov
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Tejun Heo
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Cc: Dave Chinner
Cc: Dan Carpenter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 May, 2014
1 commit
-
debugobjects warning during netfilter exit:
------------[ cut here ]------------
WARNING: CPU: 6 PID: 4178 at lib/debugobjects.c:260 debug_print_object+0x8d/0xb0()
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20
Modules linked in:
CPU: 6 PID: 4178 Comm: kworker/u16:2 Tainted: G W 3.11.0-next-20130906-sasha #3984
Workqueue: netns cleanup_net
Call Trace:
dump_stack+0x52/0x87
warn_slowpath_common+0x8c/0xc0
warn_slowpath_fmt+0x46/0x50
debug_print_object+0x8d/0xb0
__debug_check_no_obj_freed+0xa5/0x220
debug_check_no_obj_freed+0x15/0x20
kmem_cache_free+0x197/0x340
kmem_cache_destroy+0x86/0xe0
nf_conntrack_cleanup_net_list+0x131/0x170
nf_conntrack_pernet_exit+0x5d/0x70
ops_exit_list+0x5e/0x70
cleanup_net+0xfb/0x1c0
process_one_work+0x338/0x550
worker_thread+0x215/0x350
kthread+0xe7/0xf0
ret_from_fork+0x7c/0xb0Also during dcookie cleanup:
WARNING: CPU: 12 PID: 9725 at lib/debugobjects.c:260 debug_print_object+0x8c/0xb0()
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20
Modules linked in:
CPU: 12 PID: 9725 Comm: trinity-c141 Not tainted 3.15.0-rc2-next-20140423-sasha-00018-gc4ff6c4 #408
Call Trace:
dump_stack (lib/dump_stack.c:52)
warn_slowpath_common (kernel/panic.c:430)
warn_slowpath_fmt (kernel/panic.c:445)
debug_print_object (lib/debugobjects.c:262)
__debug_check_no_obj_freed (lib/debugobjects.c:697)
debug_check_no_obj_freed (lib/debugobjects.c:726)
kmem_cache_free (mm/slub.c:2689 mm/slub.c:2717)
kmem_cache_destroy (mm/slab_common.c:363)
dcookie_unregister (fs/dcookies.c:302 fs/dcookies.c:343)
event_buffer_release (arch/x86/oprofile/../../../drivers/oprofile/event_buffer.c:153)
__fput (fs/file_table.c:217)
____fput (fs/file_table.c:253)
task_work_run (kernel/task_work.c:125 (discriminator 1))
do_notify_resume (include/linux/tracehook.h:196 arch/x86/kernel/signal.c:751)
int_signal (arch/x86/kernel/entry_64.S:807)Sysfs has a release mechanism. Use that to release the kmem_cache
structure if CONFIG_SYSFS is enabled.Only slub is changed - slab currently only supports /proc/slabinfo and
not /sys/kernel/slab/*. We talked about adding that and someone was
working on it.[akpm@linux-foundation.org: fix CONFIG_SYSFS=n build]
[akpm@linux-foundation.org: fix CONFIG_SYSFS=n build even more]
Signed-off-by: Christoph Lameter
Reported-by: Sasha Levin
Tested-by: Sasha Levin
Acked-by: Greg KH
Cc: Thomas Gleixner
Cc: Pekka Enberg
Cc: Russell King
Cc: Bart Van Assche
Cc: Al Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Apr, 2014
1 commit
-
Currently, we try to arrange sysfs entries for memcg caches in the same
manner as for global caches. Apart from turning /sys/kernel/slab into a
mess when there are a lot of kmem-active memcgs created, it actually
does not work properly - we won't create more than one link to a memcg
cache in case its parent is merged with another cache. For instance, if
A is a root cache merged with another root cache B, we will have the
following sysfs setup:X
A -> X
B -> Xwhere X is some unique id (see create_unique_id()). Now if memcgs M and
N start to allocate from cache A (or B, which is the same), we will get:X
X:M
X:N
A -> X
B -> X
A:M -> X:M
A:N -> X:NSince B is an alias for A, we won't get entries B:M and B:N, which is
confusing.It is more logical to have entries for memcg caches under the
corresponding root cache's sysfs directory. This would allow us to keep
sysfs layout clean, and avoid such inconsistencies like one described
above.This patch does the trick. It creates a "cgroup" kset in each root
cache kobject to keep its children caches there.Signed-off-by: Vladimir Davydov
Cc: Michal Hocko
Cc: Johannes Weiner
Cc: David Rientjes
Cc: Pekka Enberg
Cc: Glauber Costa
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Nov, 2013
1 commit
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Pull SLAB changes from Pekka Enberg:
"The patches from Joonsoo Kim switch mm/slab.c to use 'struct page' for
slab internals similar to mm/slub.c. This reduces memory usage and
improves performance:https://lkml.org/lkml/2013/10/16/155
Rest of the changes are bug fixes from various people"
* 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux: (21 commits)
mm, slub: fix the typo in mm/slub.c
mm, slub: fix the typo in include/linux/slub_def.h
slub: Handle NULL parameter in kmem_cache_flags
slab: replace non-existing 'struct freelist *' with 'void *'
slab: fix to calm down kmemleak warning
slub: proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled
slab: rename slab_bufctl to slab_freelist
slab: remove useless statement for checking pfmemalloc
slab: use struct page for slab management
slab: replace free and inuse in struct slab with newly introduced active
slab: remove SLAB_LIMIT
slab: remove kmem_bufctl_t
slab: change the management method of free objects of the slab
slab: use __GFP_COMP flag for allocating slab pages
slab: use well-defined macro, virt_to_slab()
slab: overloading the RCU head over the LRU for RCU free
slab: remove cachep in struct slab_rcu
slab: remove nodeid in struct slab
slab: remove colouroff in struct slab
slab: change return type of kmem_getpages() to struct page
...
12 Nov, 2013
1 commit
-
Acked-by: Christoph Lameter
Signed-off-by: Zhi Yong Wu
Signed-off-by: Pekka Enberg
05 Sep, 2013
2 commits
-
I do not see any user for this code in the tree.
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
The kmalloc* functions of all slab allcoators are similar now so
lets move them into slab.h. This requires some function naming changes
in slob.As a results of this patch there is a common set of functions for
all allocators. Also means that kmalloc_large() is now available
in general to perform large order allocations that go directly
via the page allocator. kmalloc_large() can be substituted if
kmalloc() throws warnings because of too large allocations.kmalloc_large() has exactly the same semantics as kmalloc but
can only used for allocations > PAGE_SIZE.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
01 Feb, 2013
5 commits
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Put the definitions for the kmem_cache_node structures together so that
we have one structure. That will allow us to create more common fields in
the future which could yield more opportunities to share code.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Extract the optimized lookup functions from slub and put them into
slab_common.c. Then make slab use these functions as well.Joonsoo notes that this fixes some issues with constant folding which
also reduces the code size for slub.https://lkml.org/lkml/2012/10/20/82
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Have a common definition fo the kmalloc cache arrays in
SLAB and SLUBAcked-by: Glauber Costa
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Standardize the constants that describe the smallest and largest
object kept in the kmalloc arrays for SLAB and SLUB.Differentiate between the maximum size for which a slab cache is used
(KMALLOC_MAX_CACHE_SIZE) and the maximum allocatable size
(KMALLOC_MAX_SIZE, KMALLOC_MAX_ORDER).Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Extract the function to determine the index of the slab within
the array of kmalloc caches as well as a function to determine
maximum object size from the nr of the kmalloc slab.This is used here only to simplify slub bootstrap but will
be used later also for SLAB.Acked-by: Glauber Costa
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
19 Dec, 2012
3 commits
-
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Frederic Weisbecker
Cc: Greg Thelen
Cc: Johannes Weiner
Cc: JoonSoo Kim
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Pekka Enberg
Cc: Rik van Riel
Cc: Suleiman Souhlal
Cc: Tejun Heo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We are able to match a cache allocation to a particular memcg. If the
task doesn't change groups during the allocation itself - a rare event,
this will give us a good picture about who is the first group to touch a
cache page.This patch uses the now available infrastructure by calling
memcg_kmem_get_cache() before all the cache allocations.Signed-off-by: Glauber Costa
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Frederic Weisbecker
Cc: Greg Thelen
Cc: Johannes Weiner
Cc: JoonSoo Kim
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Pekka Enberg
Cc: Rik van Riel
Cc: Suleiman Souhlal
Cc: Tejun Heo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
For the kmem slab controller, we need to record some extra information in
the kmem_cache structure.Signed-off-by: Glauber Costa
Signed-off-by: Suleiman Souhlal
Cc: Christoph Lameter
Cc: David Rientjes
Cc: Frederic Weisbecker
Cc: Greg Thelen
Cc: Johannes Weiner
Cc: JoonSoo Kim
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Pekka Enberg
Cc: Rik van Riel
Cc: Tejun Heo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Jun, 2012
1 commit
-
Define a struct that describes common fields used in all slab allocators.
A slab allocator either uses the common definition (like SLOB) or is
required to provide members of kmem_cache with the definition given.After that it will be possible to share code that
only operates on those fields of kmem_cache.The patch basically takes the slob definition of kmem cache and
uses the field namees for the other allocators.It also standardizes the names used for basic object lengths in
allocators:object_size Struct size specified at kmem_cache_create. Basically
the payload expected to be used by the subsystem.size The size of memory allocator for each object. This size
is larger than object_size and includes padding, alignment
and extra metadata for each object (f.e. for debugging
and rcu).Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
01 Jun, 2012
1 commit
-
The node field is always page_to_nid(c->page). So its rather easy to
replace. Note that there maybe slightly more overhead in various hot paths
due to the need to shift the bits from page->flags. However, that is mostly
compensated for by a smaller footprint of the kmem_cache_cpu structure (this
patch reduces that to 3 words per cache) which allows better caching.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
29 Mar, 2012
1 commit
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Pull SLAB changes from Pekka Enberg:
"There's the new kmalloc_array() API, minor fixes and performance
improvements, but quite honestly, nothing terribly exciting."* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
mm: SLAB Out-of-memory diagnostics
slab: introduce kmalloc_array()
slub: per cpu partial statistics change
slub: include include for prefetch
slub: Do not hold slub_lock when calling sysfs_slab_add()
slub: prefetch next freelist pointer in slab_alloc()
slab, cleanup: remove unneeded return
05 Mar, 2012
1 commit
-
If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including and not just
expecting it to be implicitly present.We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.Signed-off-by: Paul Gortmaker
18 Feb, 2012
1 commit
-
This patch split the cpu_partial_free into 2 parts: cpu_partial_node, PCP refilling
times from node partial; and same name cpu_partial_free, PCP refilling times in
slab_free slow path. A new statistic 'cpu_partial_drain' is added to get PCP
drain to node partial times. These info are useful when do PCP tunning.The slabinfo.c code is unchanged, since cpu_partial_node is not on slow path.
Signed-off-by: Alex Shi
Acked-by: Christoph Lameter
Signed-off-by: Pekka Enberg
28 Sep, 2011
1 commit
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Correct comment errors, that mistake cpu partial objects number as pages
number, may make reader misunderstand.Signed-off-by: Alex Shi
Reviewed-by: Christoph Lameter
Signed-off-by: Pekka Enberg
20 Aug, 2011
1 commit
-
Allow filling out the rest of the kmem_cache_cpu cacheline with pointers to
partial pages. The partial page list is used in slab_free() to avoid
per node lock taking.In __slab_alloc() we can then take multiple partial pages off the per
node partial list in one go reducing node lock pressure.We can also use the per cpu partial list in slab_alloc() to avoid scanning
partial lists for pages with free objects.The main effect of a per cpu partial list is that the per node list_lock
is taken for batches of partial pages instead of individual ones.Potential future enhancements:
1. The pickup from the partial list could be perhaps be done without disabling
interrupts with some work. The free path already puts the page into the
per cpu partial list without disabling interrupts.2. __slab_free() may have some code paths that could use optimization.
Performance:
Before After
./hackbench 100 process 200000
Time: 1953.047 1564.614
./hackbench 100 process 20000
Time: 207.176 156.940
./hackbench 100 process 20000
Time: 204.468 156.940
./hackbench 100 process 20000
Time: 204.879 158.772
./hackbench 10 process 20000
Time: 20.153 15.853
./hackbench 10 process 20000
Time: 20.153 15.986
./hackbench 10 process 20000
Time: 19.363 16.111
./hackbench 1 process 20000
Time: 2.518 2.307
./hackbench 1 process 20000
Time: 2.258 2.339
./hackbench 1 process 20000
Time: 2.864 2.163Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
31 Jul, 2011
1 commit
-
* 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: (21 commits)
slub: When allocating a new slab also prep the first object
slub: disable interrupts in cmpxchg_double_slab when falling back to pagelock
Avoid duplicate _count variables in page_struct
Revert "SLUB: Fix build breakage in linux/mm_types.h"
SLUB: Fix build breakage in linux/mm_types.h
slub: slabinfo update for cmpxchg handling
slub: Not necessary to check for empty slab on load_freelist
slub: fast release on full slab
slub: Add statistics for the case that the current slab does not match the node
slub: Get rid of the another_slab label
slub: Avoid disabling interrupts in free slowpath
slub: Disable interrupts in free_debug processing
slub: Invert locking and avoid slab lock
slub: Rework allocator fastpaths
slub: Pass kmem_cache struct to lock and freeze slab
slub: explicit list_lock taking
slub: Add cmpxchg_double_slab()
mm: Rearrange struct page
slub: Move page->frozen handling near where the page->freelist handling occurs
slub: Do not use frozen page flag but a bit in the page counters
...
08 Jul, 2011
1 commit
-
This is for tracking down suspect memory usage.
Acked-by: Christoph Lameter
Signed-off-by: Ben Greear
Signed-off-by: Pekka Enberg
02 Jul, 2011
3 commits
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Make deactivation occur implicitly while checking out the current freelist.
This avoids one cmpxchg operation on a slab that is now fully in use.
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Slub reloads the per cpu slab if the page does not satisfy the NUMA condition. Track
those reloads since doing so has a performance impact.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Add a function that operates on the second doubleword in the page struct
and manipulates the object counters, the freelist and the frozen attribute.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
17 Jun, 2011
1 commit
-
Every slab has its on alignment definition in include/linux/sl?b_def.h. Extract those
and define a common set in include/linux/slab.h.SLOB: As notes sometimes we need double word alignment on 32 bit. This gives all
structures allocated by SLOB a unsigned long long alignment like the others do.SLAB: If ARCH_SLAB_MINALIGN is not set SLAB would set ARCH_SLAB_MINALIGN to
zero meaning no alignment at all. Give it the default unsigned long long alignment.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
21 May, 2011
1 commit
-
kmalloc_index() currently returns -1 if the PAGE_SIZE is larger than 2M
which seems to cause some concern since the callers do not check for -1.Insert a BUG() and add a comment to the -1 explaining that the code
cannot be reached.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
08 May, 2011
1 commit
-
Remove the #ifdefs. This means that the irqsafe_cpu_cmpxchg_double() is used
everywhere.There may be performance implications since:
A. We now have to manage a transaction ID for all arches
B. The interrupt holdoff for arches not supporting CONFIG_CMPXCHG_LOCAL is reduced
to a very short irqoff section.There are no multiple irqoff/irqon sequences as a result of this change. Even in the fallback
case we only have to do one disable and enable like before.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
23 Mar, 2011
1 commit
-
Add some statistics for debugging.
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
21 Mar, 2011
1 commit
-
Conflicts:
include/linux/slub_def.h
12 Mar, 2011
1 commit
-
There is no "struct" for slub's slab, it shares with struct page.
But struct page is very small, it is insufficient when we need
to add some metadata for slab.So we add a field "reserved" to struct kmem_cache, when a slab
is allocated, kmem_cache->reserved bytes are automatically reserved
at the end of the slab for slab's metadata.Changed from v1:
Export the reserved field via sysfsAcked-by: Christoph Lameter
Signed-off-by: Lai Jiangshan
Signed-off-by: Pekka Enberg
11 Mar, 2011
2 commits
-
Use the this_cpu_cmpxchg_double functionality to implement a lockless
allocation algorithm on arches that support fast this_cpu_ops.Each of the per cpu pointers is paired with a transaction id that ensures
that updates of the per cpu information can only occur in sequence on
a certain cpu.A transaction id is a "long" integer that is comprised of an event number
and the cpu number. The event number is incremented for every change to the
per cpu state. This means that the cmpxchg instruction can verify for an
update that nothing interfered and that we are updating the percpu structure
for the processor where we picked up the information and that we are also
currently on that processor when we update the information.This results in a significant decrease of the overhead in the fastpaths. It
also makes it easy to adopt the fast path for realtime kernels since this
is lockless and does not require the use of the current per cpu area
over the critical section. It is only important that the per cpu area is
current at the beginning of the critical section and at the end.So there is no need even to disable preemption.
Test results show that the fastpath cycle count is reduced by up to ~ 40%
(alloc/free test goes from ~140 cycles down to ~80). The slowpath for kfree
adds a few cycles.Sadly this does nothing for the slowpath which is where the main issues with
performance in slub are but the best case performance rises significantly.
(For that see the more complex slub patches that require cmpxchg_double)Kmalloc: alloc/free test
Before:
10000 times kmalloc(8)/kfree -> 134 cycles
10000 times kmalloc(16)/kfree -> 152 cycles
10000 times kmalloc(32)/kfree -> 144 cycles
10000 times kmalloc(64)/kfree -> 142 cycles
10000 times kmalloc(128)/kfree -> 142 cycles
10000 times kmalloc(256)/kfree -> 132 cycles
10000 times kmalloc(512)/kfree -> 132 cycles
10000 times kmalloc(1024)/kfree -> 135 cycles
10000 times kmalloc(2048)/kfree -> 135 cycles
10000 times kmalloc(4096)/kfree -> 135 cycles
10000 times kmalloc(8192)/kfree -> 144 cycles
10000 times kmalloc(16384)/kfree -> 754 cyclesAfter:
10000 times kmalloc(8)/kfree -> 78 cycles
10000 times kmalloc(16)/kfree -> 78 cycles
10000 times kmalloc(32)/kfree -> 82 cycles
10000 times kmalloc(64)/kfree -> 88 cycles
10000 times kmalloc(128)/kfree -> 79 cycles
10000 times kmalloc(256)/kfree -> 79 cycles
10000 times kmalloc(512)/kfree -> 85 cycles
10000 times kmalloc(1024)/kfree -> 82 cycles
10000 times kmalloc(2048)/kfree -> 82 cycles
10000 times kmalloc(4096)/kfree -> 85 cycles
10000 times kmalloc(8192)/kfree -> 82 cycles
10000 times kmalloc(16384)/kfree -> 706 cyclesKmalloc: Repeatedly allocate then free test
Before:
10000 times kmalloc(8) -> 211 cycles kfree -> 113 cycles
10000 times kmalloc(16) -> 174 cycles kfree -> 115 cycles
10000 times kmalloc(32) -> 235 cycles kfree -> 129 cycles
10000 times kmalloc(64) -> 222 cycles kfree -> 120 cycles
10000 times kmalloc(128) -> 343 cycles kfree -> 139 cycles
10000 times kmalloc(256) -> 827 cycles kfree -> 147 cycles
10000 times kmalloc(512) -> 1048 cycles kfree -> 272 cycles
10000 times kmalloc(1024) -> 2043 cycles kfree -> 528 cycles
10000 times kmalloc(2048) -> 4002 cycles kfree -> 571 cycles
10000 times kmalloc(4096) -> 7740 cycles kfree -> 628 cycles
10000 times kmalloc(8192) -> 8062 cycles kfree -> 850 cycles
10000 times kmalloc(16384) -> 8895 cycles kfree -> 1249 cyclesAfter:
10000 times kmalloc(8) -> 190 cycles kfree -> 129 cycles
10000 times kmalloc(16) -> 76 cycles kfree -> 123 cycles
10000 times kmalloc(32) -> 126 cycles kfree -> 124 cycles
10000 times kmalloc(64) -> 181 cycles kfree -> 128 cycles
10000 times kmalloc(128) -> 310 cycles kfree -> 140 cycles
10000 times kmalloc(256) -> 809 cycles kfree -> 165 cycles
10000 times kmalloc(512) -> 1005 cycles kfree -> 269 cycles
10000 times kmalloc(1024) -> 1999 cycles kfree -> 527 cycles
10000 times kmalloc(2048) -> 3967 cycles kfree -> 570 cycles
10000 times kmalloc(4096) -> 7658 cycles kfree -> 637 cycles
10000 times kmalloc(8192) -> 8111 cycles kfree -> 859 cycles
10000 times kmalloc(16384) -> 8791 cycles kfree -> 1173 cyclesSigned-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
It is used in unfreeze_slab() which is a performance critical
function.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg