Date: Sat, 24 Jun 2006 21:52:03 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-stable@freebsd.org, Dmitry Morozovsky <marck@rinet.ru> Subject: Re: vmstat 'b' (disk busy?) field keeps climbing ... Message-ID: <20060624185203.GC79678@deviant.kiev.zoral.com.ua> In-Reply-To: <20060624145432.A1114@ganymede.hub.org> References: <20060623172557.H1114@ganymede.hub.org> <261AD16B-C3FE-4671-996E-563053508CE8@mac.com> <20060624022227.X1114@ganymede.hub.org> <20060624115505.E14669@woozle.rinet.ru> <20060624090656.GB79678@deviant.kiev.zoral.com.ua> <20060624145432.A1114@ganymede.hub.org>
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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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