linux/Documentation/filesystems
KOSAKI Motohiro 1306d603fc 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>
2010-01-11 09:34:06 -08:00
..
caching CacheFiles: Catch an overly long wait for an old active object 2009-11-19 18:12:05 +00:00
configfs docsrc: build Documentation/ sources 2008-08-12 16:07:30 -07:00
nfs nfs: move more to Documentation/filesystems/nfs 2009-11-06 14:01:02 -05:00
pohmelfs Staging: Pohmelfs: Added IO permissions and priorities. 2009-04-17 11:06:30 -07:00
00-INDEX Merge branch 'for-2.6.33' of git://linux-nfs.org/~bfields/linux 2009-12-16 10:43:34 -08:00
9p.txt 9p: Update documentation to add fscache related bits 2009-09-23 13:03:46 -05:00
adfs.txt
affs.txt
afs.txt AFS: Documentation updates 2009-08-19 10:40:13 -07:00
autofs4-mount-control.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
automount-support.txt
befs.txt
bfs.txt remove mention of CONFIG_KMOD from documentation 2008-07-22 19:24:29 +10:00
btrfs.txt Btrfs: Add Documentation/filesystem/btrfs.txt, remove old COPYING 2009-01-07 09:54:24 -05:00
cifs.txt
coda.txt
cramfs.txt
debugfs.txt Document the debugfs API 2009-06-06 10:28:14 -06:00
dentry-locking.txt
devpts.txt Document usage of multiple-instances of devpts 2009-01-02 10:19:36 -08:00
directory-locking
dlmfs.txt
dnotify.txt
ecryptfs.txt
exofs.txt trivial: some small fixes in exofs documentation 2009-12-10 09:59:16 +02:00
ext2.txt Doc fix: ext2 can only have 32,000 subdirs, not 32,768 2009-06-18 13:03:44 -07:00
ext3.txt ext3: make "norecovery" an alias for "noload" 2009-12-10 15:02:52 +01:00
ext4.txt ext4: Update documentation to correct the inode_readahead_blks option name 2009-12-24 17:51:42 -05:00
fiemap.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
files.txt fix f_count description in Documentation/filesystems/files.txt 2008-12-31 18:07:42 -05:00
fuse.txt
gfs2-glocks.txt GFS2: Update docs 2009-05-19 10:23:23 +01:00
gfs2-uevents.txt GFS2: Add a document explaining GFS2's uevents 2009-08-17 11:11:41 +01:00
gfs2.txt GFS2: Update docs 2009-05-19 10:23:23 +01:00
hfs.txt
hfsplus.txt
hpfs.txt
inotify.txt
isofs.txt isofs: let mode and dmode mount options override rock ridge mode setting 2009-06-18 13:03:45 -07:00
jfs.txt
Locking update Documentation/filesystems/Locking 2009-06-24 08:15:25 -04:00
locks.txt
mandatory-locking.txt
ncpfs.txt ncpfs: remove dead URL from documentation 2009-09-23 07:39:42 -07:00
nilfs2.txt nilfs2: update mailing list address 2010-01-02 21:47:04 +09:00
ntfs.txt NTFS: update homepage 2008-09-02 19:21:37 -07:00
ocfs2.txt ocfs2: Refresh documentation 2009-11-13 15:45:01 -08:00
omfs.txt omfs: add filesystem documentation 2008-07-26 12:00:05 -07:00
porting nfs: new subdir Documentation/filesystems/nfs 2009-10-27 19:34:04 -04:00
proc.txt proc: partially revert "procfs: provide stack information for threads" 2010-01-11 09:34:06 -08:00
quota.txt quota: documentation for sending "below quota" messages via netlink and tiny doc update 2008-08-12 16:07:27 -07:00
ramfs-rootfs-initramfs.txt Trivial Documentation/filesystems/ramfs-rootfs-initramfs.txt fix 2008-11-30 11:40:56 -08:00
relay.txt relay: add buffer-only channels; useful for early logging 2008-07-26 12:00:04 -07:00
romfs.txt
seq_file.txt seq_file: use proc_create() in documentation 2009-12-16 07:20:07 -08:00
sharedsubtree.txt doc/filesystems: more mount cleanups 2009-09-24 07:20:57 -07:00
smbfs.txt
spufs.txt
squashfs.txt Squashfs: fix documentation typo, Cramfs filesystem limit is 256 MiB 2009-03-05 00:40:13 +00:00
sysfs-pci.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
sysfs.txt Driver core: driver_attribute parameters can often be const* 2009-12-23 11:23:43 -08:00
sysv-fs.txt
tmpfs.txt hugh: update email address 2009-05-21 13:14:32 -07:00
ubifs.txt UBIFS: remove fast unmounting 2009-01-29 16:34:30 +02:00
udf.txt udf: implement mode and dmode mounting options 2009-04-02 12:29:50 +02:00
ufs.txt
vfat.txt vfat: change the default from shortname=lower to shortname=mixed 2009-08-01 21:35:25 +09:00
vfs.txt kill wait_on_page_writeback_range 2009-12-10 15:02:50 +01:00
xfs.txt [XFS] remove restricted chown parameter from xfs linux 2008-10-30 18:30:09 +11:00
xip.txt DOC: update xip method info 2008-11-12 17:17:17 -08:00