Re: 2.6.17-mm6 vmstat breakage

[Andrew Morton <akpm@osdl.org>]

On Thu, 06 Jul 2006 09:38:43 +0200
Mike Galbraith <efault@gmx.de> wrote:

> Greetings,
> 
> My single P4/HT box is showing incorrect pgpgin pgpgout numbers with
> this kernel.  While disk throughput for dd if=/dev/hdc of=/dev=null
> bs=4096 count=1000000 produces about 57MB/S (up ~14% over 2.6.17 btw),
> vmstat (procps version 3.2.5) is only showing about 7MB/S.
> 
> Looking at the numbers in /proc/vmstat, it looks kinda like pgpgin might
> be pages instead of the KB it used to be, with some added >>=1 action on
> the side.  At any rate, the numbers below are horse-pookey ;-)
> 
>  procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
>  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
>  1  1   3820   9400 810128  46052    0    0  7040     0 1163  1283  2  7 48 44
>  1  1   3820   9220 810288  46156    0    0  7040     0 1151  1335  3  6 48 45
>  1  1   3820   9280 810176  46204    0    0  7168     0 1156  1207  1  7 48 44
>  2  1   3820   9408 810048  46068    0    0  7168     0 1160  1192  1  6 49 46
> 

2.6.18-rc1 has the same bug.

--- a/include/linux/vmstat.h~count_vm_events-fix
+++ a/include/linux/vmstat.h
@@ -57,7 +57,7 @@ static inline void __count_vm_events(enu
 
 static inline void count_vm_events(enum vm_event_item item, long delta)
 {
-	get_cpu_var(vm_event_states.event[item])++;
+	get_cpu_var(vm_event_states.event[item]) += delta;
 	put_cpu();
 }
 
_

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