27 May, 2011
40 commits
-
Setup and cleanup of mm_struct->exe_file is currently done in fs/proc/.
This was because exe_file was needed only for /proc//exe. Since we
will need the exe_file functionality also for core dumps (so core name can
contain full binary path), built this functionality always into the
kernel.To achieve that move that out of proc FS to the kernel/ where in fact it
should belong. By doing that we can make dup_mm_exe_file static. Also we
can drop linux/proc_fs.h inclusion in fs/exec.c and kernel/fork.c.Signed-off-by: Jiri Slaby
Cc: Alexander Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The Blackfin arch, like the x86 arch, needs to adjust the PC manually
after a breakpoint is hit as normally this is handled by the remote gdb.
However, rather than starting another arch ifdef mess, create a common
GDB_ADJUSTS_BREAK_OFFSET define for any arch to opt-in via their kgdb.h.Signed-off-by: Mike Frysinger
Cc: Oleg Nesterov
Cc: Jason Wessel
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Acked-by: Paul Mundt
Acked-by: Dongdong Deng
Cc: Sergei Shtylyov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Mike Frysinger
Cc: Oleg Nesterov
Cc: Jason Wessel
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Paul Mundt
Cc: Sergei Shtylyov
Cc: Dongdong Deng
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Mike Frysinger
Cc: Oleg Nesterov
Cc: Jason Wessel
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Paul Mundt
Cc: Sergei Shtylyov
Cc: Dongdong Deng
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Mike Frysinger
Cc: Oleg Nesterov
Cc: Jason Wessel
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Paul Mundt
Cc: Sergei Shtylyov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This is a series of low level ptrace unification steps to make it easier
for common code (like KGDB) to poke at register state. This also avoids
having to duplicate higher level operations for most ports which don't
have special needs for accessing things.This patch:
This implements a bunch of helper funcs for poking the registers of a
ptrace structure. Now common code should be able to portably update
specific registers (like kgdb updating the PC).Signed-off-by: Mike Frysinger
Cc: Oleg Nesterov
Cc: Jason Wessel
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Paul Mundt
Cc: Sergei Shtylyov
Cc: Dongdong Deng
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Two new stats in per-memcg memory.stat which tracks the number of page
faults and number of major page faults."pgfault"
"pgmajfault"They are different from "pgpgin"/"pgpgout" stat which count number of
pages charged/discharged to the cgroup and have no meaning of reading/
writing page to disk.It is valuable to track the two stats for both measuring application's
performance as well as the efficiency of the kernel page reclaim path.
Counting pagefaults per process is useful, but we also need the aggregated
value since processes are monitored and controlled in cgroup basis in
memcg.Functional test: check the total number of pgfault/pgmajfault of all
memcgs and compare with global vmstat value:$ cat /proc/vmstat | grep fault
pgfault 1070751
pgmajfault 553$ cat /dev/cgroup/memory.stat | grep fault
pgfault 1071138
pgmajfault 553
total_pgfault 1071142
total_pgmajfault 553$ cat /dev/cgroup/A/memory.stat | grep fault
pgfault 199
pgmajfault 0
total_pgfault 199
total_pgmajfault 0Performance test: run page fault test(pft) wit 16 thread on faulting in
15G anon pages in 16G container. There is no regression noticed on the
"flt/cpu/s"Sample output from pft:
TAG pft:anon-sys-default:
Gb Thr CLine User System Wall flt/cpu/s fault/wsec
15 16 1 0.67s 233.41s 14.76s 16798.546 266356.260+-------------------------------------------------------------------------+
N Min Max Median Avg Stddev
x 10 16682.962 17344.027 16913.524 16928.812 166.5362
+ 10 16695.568 16923.896 16820.604 16824.652 84.816568
No difference proven at 95.0% confidence[akpm@linux-foundation.org: fix build]
[hughd@google.com: shmem fix]
Signed-off-by: Ying Han
Acked-by: KAMEZAWA Hiroyuki
Cc: KOSAKI Motohiro
Reviewed-by: Minchan Kim
Cc: Daisuke Nishimura
Acked-by: Balbir Singh
Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The new API exports numa_maps per-memcg basis. This is a piece of useful
information where it exports per-memcg page distribution across real numa
nodes.One of the usecases is evaluating application performance by combining
this information w/ the cpu allocation to the application.The output of the memory.numastat tries to follow w/ simiar format of
numa_maps like:total= N0= N1= ...
file= N0= N1= ...
anon= N0= N1= ...
unevictable= N0= N1= ...And we have per-node:
total = file + anon + unevictable
$ cat /dev/cgroup/memory/memory.numa_stat
total=250020 N0=87620 N1=52367 N2=45298 N3=64735
file=225232 N0=83402 N1=46160 N2=40522 N3=55148
anon=21053 N0=3424 N1=6207 N2=4776 N3=6646
unevictable=3735 N0=794 N1=0 N2=0 N3=2941Signed-off-by: Ying Han
Cc: Balbir Singh
Cc: Daisuke Nishimura
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Daisuke Nishimura
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The caller of the function has been renamed to zone_nr_lru_pages(), and
this is just fixing up in the memcg code. The current name is easily to
be mis-read as zone's total number of pages.Signed-off-by: Ying Han
Acked-by: Johannes Weiner
Acked-by: KAMEZAWA Hiroyuki
Reviewed-by: Minchan Kim
Cc: Balbir Singh
Cc: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
If the memcg reclaim code detects the target memcg below its limit it
exits and returns a guaranteed non-zero value so that the charge is
retried.Nowadays, the charge side checks the memcg limit itself and does not rely
on this non-zero return value trick.This patch removes it. The reclaim code will now always return the true
number of pages it reclaimed on its own.Signed-off-by: Johannes Weiner
Acked-by: Rik van Riel
Acked-by: Ying Han
Acked-by: KAMEZAWA Hiroyuki
Reviewed-by: Michal Hocko
Cc: Balbir Singh
Cc: KOSAKI Motohiro
Cc: Mel Gorman
Cc: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
During memory reclaim we determine the number of pages to be scanned per
zone as(anon + file) >> priority.
Assume
scan = (anon + file) >> priority.If scan < SWAP_CLUSTER_MAX, the scan will be skipped for this time and
priority gets higher. This has some problems.1. This increases priority as 1 without any scan.
To do scan in this priority, amount of pages should be larger than 512M.
If pages>>priority < SWAP_CLUSTER_MAX, it's recorded and scan will be
batched, later. (But we lose 1 priority.)
If memory size is below 16M, pages >> priority is 0 and no scan in
DEF_PRIORITY forever.2. If zone->all_unreclaimabe==true, it's scanned only when priority==0.
So, x86's ZONE_DMA will never be recoverred until the user of pages
frees memory by itself.3. With memcg, the limit of memory can be small. When using small memcg,
it gets priority < DEF_PRIORITY-2 very easily and need to call
wait_iff_congested().
For doing scan before priorty=9, 64MB of memory should be used.Then, this patch tries to scan SWAP_CLUSTER_MAX of pages in force...when
1. the target is enough small.
2. it's kswapd or memcg reclaim.Then we can avoid rapid priority drop and may be able to recover
all_unreclaimable in a small zones. And this patch removes nr_saved_scan.
This will allow scanning in this priority even when pages >> priority is
very small.Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Ying Han
Cc: Balbir Singh
Cc: KOSAKI Motohiro
Cc: Daisuke Nishimura
Cc: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Presently, memory cgroup's direct reclaim frees memory from the current
node. But this has some troubles. Usually when a set of threads works in
a cooperative way, they tend to operate on the same node. So if they hit
limits under memcg they will reclaim memory from themselves, damaging the
active working set.For example, assume 2 node system which has Node 0 and Node 1 and a memcg
which has 1G limit. After some work, file cache remains and the usages
areNode 0: 1M
Node 1: 998M.and run an application on Node 0, it will eat its foot before freeing
unnecessary file caches.This patch adds round-robin for NUMA and adds equal pressure to each node.
When using cpuset's spread memory feature, this will work very well.But yes, a better algorithm is needed.
[akpm@linux-foundation.org: comment editing]
[kamezawa.hiroyu@jp.fujitsu.com: fix time comparisons]
Signed-off-by: Ying Han
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: KOSAKI Motohiro
Cc: Daisuke Nishimura
Cc: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
AFAICS mm/page_cgroup.c is for memcg subsystem, but it was directed only
to generic cgroup maintainers. Fix it.Signed-off-by: Namhyung Kim
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: KAMEZAWA Hiroyuki
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Move page-freeing code out of swap_cgroup_mutex in the hope that it could
reduce few of theoretical contentions between swapons and/or swapoffs.This is just a cleanup, no functional changes.
Signed-off-by: Namhyung Kim
Acked-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
It allocated one more page than necessary if @max_pages was a multiple of
SC_PER_PAGE.Signed-off-by: Namhyung Kim
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Cc: Daisuke Nishimura
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit ca371c0d7e23 ("memcg: fix page_cgroup fatal error in FLATMEM")
removes call to alloc_bootmem() in the function so that it can be marked
as __meminit to reduce memory usage when MEMORY_HOTPLUG=n.Also as the new helper function alloc_page_cgroup() is called only in the
function, it should be marked too.Signed-off-by: Namhyung Kim
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Cc: Michal Hocko
Cc: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
next_mz is assigned to NULL if __mem_cgroup_largest_soft_limit_node
selects the same mz. This doesn't make much sense as we assign to the
variable right in the next loop.Compiler will probably optimize this out but it is little bit confusing
for the code reading.Signed-off-by: Michal Hocko
Acked-by: Daisuke Nishimura
Cc: Balbir Singh
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We recently added the change in global background reclaim which counts the
return value of soft_limit reclaim. Now this patch adds the similar logic
on global direct reclaim.We should skip scanning global LRU on shrink_zone if soft_limit reclaim
does enough work. This is the first step where we start with counting the
nr_scanned and nr_reclaimed from soft_limit reclaim into global
scan_control.Signed-off-by: Ying Han
Cc: KOSAKI Motohiro
Cc: Minchan Kim
Cc: Daisuke Nishimura
Cc: Balbir Singh
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Rik van Riel
Cc: Hugh Dickins
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The global kswapd scans per-zone LRU and reclaims pages regardless of the
cgroup. It breaks memory isolation since one cgroup can end up reclaiming
pages from another cgroup. Instead we should rely on memcg-aware target
reclaim including per-memcg kswapd and soft_limit hierarchical reclaim under
memory pressure.In the global background reclaim, we do soft reclaim before scanning the
per-zone LRU. However, the return value is ignored. This patch is the first
step to skip shrink_zone() if soft_limit reclaim does enough work.This is part of the effort which tries to reduce reclaiming pages in global
LRU in memcg. The per-memcg background reclaim patchset further enhances the
per-cgroup targetting reclaim, which I should have V4 posted shortly.Try running multiple memory intensive workloads within seperate memcgs. Watch
the counters of soft_steal in memory.stat.$ cat /dev/cgroup/A/memory.stat | grep 'soft'
soft_steal 240000
soft_scan 240000
total_soft_steal 240000
total_soft_scan 240000This patch:
In the global background reclaim, we do soft reclaim before scanning the
per-zone LRU. However, the return value is ignored.We would like to skip shrink_zone() if soft_limit reclaim does enough
work. Also, we need to make the memory pressure balanced across per-memcg
zones, like the logic vm-core. This patch is the first step where we
start with counting the nr_scanned and nr_reclaimed from soft_limit
reclaim into the global scan_control.Signed-off-by: Ying Han
Cc: KOSAKI Motohiro
Cc: Minchan Kim
Cc: Rik van Riel
Cc: Mel Gorman
Cc: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Acked-by: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
enums are problematic because they cannot be forward-declared:
akpm2:/home/akpm> cat t.c
enum foo;
static inline void bar(enum foo f)
{
}
akpm2:/home/akpm> gcc -c t.c
t.c:4: error: parameter 1 ('f') has incomplete typeSo move the enum's definition into a standalone header file which can be used
wherever its definition is needed.Cc: Ying Han
Cc: KAMEZAWA Hiroyuki
Cc: KOSAKI Motohiro
Cc: Minchan Kim
Cc: Daisuke Nishimura
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and
leads to some problems:* cgroup creation is out-of-control
* cgroup name can conflict when pids are looping
* it is not possible to have a single process handling a lot of
namespaces without falling in a exponential creation time
* we may want to create a namespace without creating a cgroupThe ns_cgroup was replaced by a compatibility flag 'clone_children',
where a newly created cgroup will copy the parent cgroup values.
The userspace has to manually create a cgroup and add a task to
the 'tasks' file.This patch removes the ns_cgroup as suggested in the following thread:
https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html
The 'cgroup_clone' function is removed because it is no longer used.
This is a userspace-visible change. Commit 45531757b45c ("cgroup: notify
ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a
printk warning users that the feature is planned for removal. Since that
time we have heard from XXX users who were affected by this.Signed-off-by: Daniel Lezcano
Signed-off-by: Serge E. Hallyn
Cc: Eric W. Biederman
Cc: Jamal Hadi Salim
Reviewed-by: Li Zefan
Acked-by: Paul Menage
Acked-by: Matt Helsley
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Convert cgroup_attach_proc to use flex_array.
The cgroup_attach_proc implementation requires a pre-allocated array to
store task pointers to atomically move a thread-group, but asking for a
monolithic array with kmalloc() may be unreliable for very large groups.
Using flex_array provides the same functionality with less risk of
failure.This is a post-patch for cgroup-procs-write.patch.
Signed-off-by: Ben Blum
Cc: "Eric W. Biederman"
Cc: Li Zefan
Cc: Matt Helsley
Reviewed-by: Paul Menage
Cc: Oleg Nesterov
Cc: David Rientjes
Cc: Miao Xie
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Make procs file writable to move all threads by tgid at once.
Add functionality that enables users to move all threads in a threadgroup
at once to a cgroup by writing the tgid to the 'cgroup.procs' file. This
current implementation makes use of a per-threadgroup rwsem that's taken
for reading in the fork() path to prevent newly forking threads within the
threadgroup from "escaping" while the move is in progress.Signed-off-by: Ben Blum
Cc: "Eric W. Biederman"
Cc: Li Zefan
Cc: Matt Helsley
Reviewed-by: Paul Menage
Cc: Oleg Nesterov
Cc: David Rientjes
Cc: Miao Xie
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add cgroup subsystem callbacks for per-thread attachment in atomic contexts
Add can_attach_task(), pre_attach(), and attach_task() as new callbacks
for cgroups's subsystem interface. Unlike can_attach and attach, these
are for per-thread operations, to be called potentially many times when
attaching an entire threadgroup.Also, the old "bool threadgroup" interface is removed, as replaced by
this. All subsystems are modified for the new interface - of note is
cpuset, which requires from/to nodemasks for attach to be globally scoped
(though per-cpuset would work too) to persist from its pre_attach to
attach_task and attach.This is a pre-patch for cgroup-procs-writable.patch.
Signed-off-by: Ben Blum
Cc: "Eric W. Biederman"
Cc: Li Zefan
Cc: Matt Helsley
Reviewed-by: Paul Menage
Cc: Oleg Nesterov
Cc: David Rientjes
Cc: Miao Xie
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Adds functionality to read/write lock CLONE_THREAD fork()ing per-threadgroup
Add an rwsem that lives in a threadgroup's signal_struct that's taken for
reading in the fork path, under CONFIG_CGROUPS. If another part of the
kernel later wants to use such a locking mechanism, the CONFIG_CGROUPS
ifdefs should be changed to a higher-up flag that CGROUPS and the other
system would both depend on.This is a pre-patch for cgroup-procs-write.patch.
Signed-off-by: Ben Blum
Cc: "Eric W. Biederman"
Cc: Li Zefan
Cc: Matt Helsley
Reviewed-by: Paul Menage
Cc: Oleg Nesterov
Cc: David Rientjes
Cc: Miao Xie
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When configfs_register_subsystem() fails, we unregister too many
subsystems in configfs_example_init. Decrement i by one to not unregister
non-registered subsystem.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jiri Slaby
Cc: Joel Becker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I find it very handy to show the average delays in milliseconds.
Example output (on 100 concurrent dd reading sparse files):
CPU count real total virtual total delay total delay average
986 3223509952 3207643301 38863410579 39.415ms
IO count delay total delay average
0 0 0ms
SWAP count delay total delay average
0 0 0ms
RECLAIM count delay total delay average
1059 5131834899 4ms
dd: read=0, write=0, cancelled_write=0Signed-off-by: Wu Fengguang
Cc: Mel Gorman
Cc: Balbir Singh
Reviewed-by: Satoru Moriya
Reviewed-by: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fixes
Documentation/accounting/getdelays.c: In function `get_family_id':
Documentation/accounting/getdelays.c:172:14: warning: variable `rc' set but not used [-Wunused-but-set-variable]Reported-by: "Justin P. Mattock"
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fixes
Documentation/accounting/getdelays.c: In function `main':
Documentation/accounting/getdelays.c:436:7: warning: variable `i' set but not used [-Wunused-but-set-variable]Signed-off-by: Justin P. Mattock
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
As declaring counter as volatile is discouraged, it is best not to use it
in sample code as well.Signed-off-by: Nikanth Karthikesan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Originally i_lastfrag was 32 bits but then we added support for handling
64 bit metadata and it became a 64 bit variable. That was during 2007, in
54fb996ac15c "[PATCH] ufs2 write: block allocation update". Unfortunately
these casts got left behind so the value got truncated to 32 bit again.[akpm@linux-foundation.org: remove now-unneeded min_t/max_t casting]
Signed-off-by: Dan Carpenter
Cc: Evgeniy Dushistov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
[akpm@linux-foundation.org: retain the code comments]
Signed-off-by: Wolfram Sang
Cc: Vladimir Zapolskiy
Cc: Alessandro Zummo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit 51ba60c5 ("RTC: Cleanup rtc_class_ops->update_irq_enable()")
removed the only user of the update IRQ, so there is no need to manage it
any more.Signed-off-by: Lars-Peter Clausen
Cc: Thomas Gleixner
Cc: Alessandro Zummo
Cc: Marcelo Roberto Jimenez
Cc: John Stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Rajeev Kumar
Signed-off-by: Viresh Kumar
Cc: Alessandro Zummo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The memory allocated using request_mem_region should be released using
release_mem_region, not release_region.The semantic patch that fixes part of this problem is as follows:
(http://coccinelle.lip6.fr/)//
@@
expression E1,E2,E3;
@@request_mem_region(E1,E2,E3)
...
?- release_region(E1,E2)
+ release_mem_region(E1,E2)
//[akpm@linux-foundation.org: use resource_size()]
Signed-off-by: Julia Lawall
Cc: Alessandro Zummo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add basic support for ST m41t93 SPI RTCs. Tested with factory-new and
with "run-in" species with and without backup batteries.Signed-off-by: Nikolaus Voss
Cc: Alessandro Zummo
Cc: Grant Likely
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add support for the Micro Crystal RV3029-C2 RTC chips.
Signed-off-by: Heiko Schocher
Signed-off-by: Gregory Hermant
Cc: Wan ZongShun
Cc: Alessandro Zummo
Acked-by: Wolfram Sang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add support for EM Microelectronic EM3027 RTC chip.
Signed-off-by: Mike Rapoport
Cc: Alessandro Zummo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This adds a driver for the RTC devices in VIA and WonderMedia
Systems-on-Chip. Alarm, 1Hz interrupts, reading and setting time are
supported.Signed-off-by: Alexey Charkov
Cc: Lars-Peter Clausen
Cc: Alexey Charkov
Cc: Alessandro Zummo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
On most architectures division is an expensive operation and accessing an
element currently requires four of them. This performance penalty
effectively precludes flex arrays from being used on any kind of fast
path. However, two of these divisions can be handled at creation time and
the others can be replaced by a reciprocal divide, completely avoiding
real divisions on access.[eparis@redhat.com: rebase on top of changes to support 0 len elements]
[eparis@redhat.com: initialize part_nr when array fits entirely in base]
Signed-off-by: Jesse Gross
Signed-off-by: Eric Paris
Cc: Dave Hansen
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
