proc: faster /proc/$PID lookup
authorAlexey Dobriyan <adobriyan@gmail.com>
Fri, 8 Aug 2014 21:21:27 +0000 (14:21 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 8 Aug 2014 22:57:22 +0000 (15:57 -0700)
commit335eb53158466a4c4d018fa53ceb8c8ba1067fa3
treef12db91b65fa3ea85bad2610aab8dfa3d8f4dfc8
parentdbcdb504417ae108a20454ef89776a614b948571
proc: faster /proc/$PID lookup

Currently lookup for /proc/$PID first goes through spinlock and whole list
of misc /proc entries only to confirm that, yes, /proc/42 can not possibly
match random proc entry.

List is is several dozens entries long (52 entries on my setup).

None of this is necessary.

Try to convert dentry name to integer first.
If it works, it must be /proc/$PID.
If it doesn't, it must be random proc entry.

Based on patch from Al Viro.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/base.c
fs/proc/root.c