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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2018-04-10 16:30:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-11 10:28:33 -0700 |
| commit | 2f8974243507d9e5b0f214d7668a59a66b93f36c (patch) | |
| tree | daef514c815b0989ca99ccf67d8725d9262c7d56 /ipc | |
| parent | 68c3411ff4a4cee53cc854c11ed191eaaf1956ba (diff) | |
| download | op-kernel-dev-2f8974243507d9e5b0f214d7668a59a66b93f36c.zip op-kernel-dev-2f8974243507d9e5b0f214d7668a59a66b93f36c.tar.gz | |
proc: do less stuff under ->pde_unload_lock
Commit ca469f35a8e9ef ("deal with races between remove_proc_entry() and
proc_reg_release()") moved too much stuff under ->pde_unload_lock making
a problem described at series "[PATCH v5] procfs: Improve Scaling in
proc" worse.
While RCU is being figured out, move kfree() out of ->pde_unload_lock.
On my potato, difference is only 0.5% speedup with concurrent
open+read+close of /proc/cmdline, but the effect should be more
noticeable on more capable machines.
$ perf stat -r 16 -- ./proc-j 16
Performance counter stats for './proc-j 16' (16 runs):
130569.502377 task-clock (msec) # 15.872 CPUs utilized ( +- 0.05% )
19,169 context-switches # 0.147 K/sec ( +- 0.18% )
15 cpu-migrations # 0.000 K/sec ( +- 3.27% )
437 page-faults # 0.003 K/sec ( +- 1.25% )
300,172,097,675 cycles # 2.299 GHz ( +- 0.05% )
96,793,267,308 instructions # 0.32 insn per cycle ( +- 0.04% )
22,798,342,298 branches # 174.607 M/sec ( +- 0.04% )
111,764,687 branch-misses # 0.49% of all branches ( +- 0.47% )
8.226574400 seconds time elapsed ( +- 0.05% )
^^^^^^^^^^^
$ perf stat -r 16 -- ./proc-j 16
Performance counter stats for './proc-j 16' (16 runs):
129866.777392 task-clock (msec) # 15.869 CPUs utilized ( +- 0.04% )
19,154 context-switches # 0.147 K/sec ( +- 0.66% )
14 cpu-migrations # 0.000 K/sec ( +- 1.73% )
431 page-faults # 0.003 K/sec ( +- 1.09% )
298,556,520,546 cycles # 2.299 GHz ( +- 0.04% )
96,525,366,833 instructions # 0.32 insn per cycle ( +- 0.04% )
22,730,194,043 branches # 175.027 M/sec ( +- 0.04% )
111,506,074 branch-misses # 0.49% of all branches ( +- 0.18% )
8.183629778 seconds time elapsed ( +- 0.04% )
^^^^^^^^^^^
Link: http://lkml.kernel.org/r/20180213132911.GA24298@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
0 files changed, 0 insertions, 0 deletions
