path: root/Documentation
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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-01-08 14:42:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-01-11 09:34:06 -0800
commit1306d603fcf1f6682f8575d1ff23631a24184b21 (patch)
tree8e2278cfabf874cb16bf03bd182ae75b87055741 /Documentation
parentf146aabfe921006b98dfa4a78506763aedfd3206 (diff)
proc: partially revert "procfs: provide stack information for threads"
Commit d899bf7b (procfs: provide stack information for threads) introduced to show stack information in /proc/{pid}/status. But it cause large performance regression. Unfortunately /proc/{pid}/status is used ps command too and ps is one of most important component. Because both to take mmap_sem and page table walk are heavily operation. If many process run, the ps performance is, [before d899bf7b] % perf stat ps >/dev/null Performance counter stats for 'ps': 4090.435806 task-clock-msecs # 0.032 CPUs 229 context-switches # 0.000 M/sec 0 CPU-migrations # 0.000 M/sec 234 page-faults # 0.000 M/sec 8587565207 cycles # 2099.425 M/sec 9866662403 instructions # 1.149 IPC 3789415411 cache-references # 926.409 M/sec 30419509 cache-misses # 7.437 M/sec 128.859521955 seconds time elapsed [after d899bf7b] % perf stat ps > /dev/null Performance counter stats for 'ps': 4305.081146 task-clock-msecs # 0.028 CPUs 480 context-switches # 0.000 M/sec 2 CPU-migrations # 0.000 M/sec 237 page-faults # 0.000 M/sec 9021211334 cycles # 2095.480 M/sec 10605887536 instructions # 1.176 IPC 3612650999 cache-references # 839.160 M/sec 23917502 cache-misses # 5.556 M/sec 152.277819582 seconds time elapsed Thus, this patch revert it. Fortunately /proc/{pid}/task/{tid}/smaps provide almost same information. we can use it. Commit d899bf7b introduced two features: 1) Add the annotattion of [thread stack: xxxx] mark to /proc/{pid}/task/{tid}/maps. 2) Add StackUsage field to /proc/{pid}/status. I only revert (2), because I haven't seen (1) cause regression. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Stefani Seibold <stefani@seibold.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
1 files changed, 0 insertions, 2 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 220cc6376ef8..0d07513a67a6 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -177,7 +177,6 @@ read the file /proc/PID/status:
CapBnd: ffffffffffffffff
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 1
- Stack usage: 12 kB
This shows you nearly the same information you would get if you viewed it with
the ps command. In fact, ps uses the proc file system to obtain its
@@ -231,7 +230,6 @@ Table 1-2: Contents of the statm files (as of 2.6.30-rc7)
Mems_allowed_list Same as previous, but in "list format"
voluntary_ctxt_switches number of voluntary context switches
nonvoluntary_ctxt_switches number of non voluntary context switches
- Stack usage: stack usage high water mark (round up to page size)
Table 1-3: Contents of the statm files (as of 2.6.8-rc3)

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