vmstat 'b' (disk busy?) field keeps climbing ...

[Kostik Belousov]

On Sat, Jun 24, 2006 at 02:57:27PM -0300, Marc G. Fournier wrote:
> On Sat, 24 Jun 2006, Kostik Belousov wrote:
> 
> >On Sat, Jun 24, 2006 at 11:55:26AM +0400, Dmitry Morozovsky wrote:
> >>On Sat, 24 Jun 2006, Marc G. Fournier wrote:
> >>
> >>MGF> > 'b' stands for "blocked", not "busy".  Judging by your page fault 
> >>rate
> >>MGF> > and the high number of frees and pages being scanned, you're 
> >>probably
> >>MGF> > swapping tasks in and out and are waiting on disk.  Take a look at
> >>MGF> > "vmstat -s", and consider adding more RAM if this is correct...
> >>MGF>
> >>MGF> is there a way of finding out what processes are blocked?
> >>
> >>Aren't they in 'D' status by ps?
> >Use ps axlww. In this way, at least actual blocking points are shown.
> 
> 'k, stupid question then ... what am I searching for?
> 
> # ps axlww | awk '{print $9}' | sort | uniq -c | sort -nr
>  654 select
>  230 lockf
>  166 wait
>   85 -
>   80 piperd
>   71 nanslp
>   33 kserel
>   22 user
>   10 pause
>    9 ttyin
>    5 sbwait
>    3 psleep
>    3 accept
>    2 kqread
>    2 Giant
>    1 vlruwt
>    1 syncer
>    1 sdflus
>    1 ppwait
>    1 ktrace
>    1 MWCHAN
> 
> According to vmstat, I'm holding at '4 blocked' for the most part ... 
> sbwwait is socket related, not disk ... and none of the others look right 
> ...
I would say, using big magic cristall ball, that you problems are
not kernel-related. I see only too suspicious points:

1. high number of pipe readers and waiters for file locks. It may be 
normal for your load.

2. 2 Giant holders/lockers. Is it constant ? Are the processes holding/waiting
for Giant are the same ?

Anyway, being in your shoes, I would start looking at applications.

Ah, and does dmesg show anything ?
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