]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
mm: fix proc_dointvec_userhz_jiffies "breakage"
authorAlexey Dobriyan <adobriyan@gmail.com>
Tue, 31 Mar 2009 22:23:18 +0000 (15:23 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 1 Apr 2009 15:59:13 +0000 (08:59 -0700)
commit704503d836042d4a4c7685b7036e7de0418fbc0f
tree218bea088f0b286981221e44d5247dab98020d30
parent6a11f75b6a17b5d9ac5025f8d048382fd1f47377
mm: fix proc_dointvec_userhz_jiffies "breakage"

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=9838

On i386, HZ=1000, jiffies_to_clock_t() converts time in a somewhat strange
way from the user's point of view:

# echo 500 >/proc/sys/vm/dirty_writeback_centisecs
# cat /proc/sys/vm/dirty_writeback_centisecs
499

So, we have 5000 jiffies converted to only 499 clock ticks and reported
back.

TICK_NSEC = 999848
ACTHZ = 256039

Keeping in-kernel variable in units passed from userspace will fix issue
of course, but this probably won't be right for every sysctl.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/writeback.h
kernel/sysctl.c
mm/page-writeback.c