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Date:      Tue, 16 Oct 2001 18:26:06 +0200
From:      Maxime Henrion <mux@qualys.com>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        cvs-all@freebsd.org, cvs-committer@freebsd.org
Subject:   Re: cvs commit: src/sys/vm vnode_pager.c
Message-ID:  <20011016182606.B469@nebula.cybercable.fr>
In-Reply-To: <200110161618.f9GGIpM31430@apollo.backplane.com>
References:  <200110121817.f9CIHYU38714@freefall.freebsd.org> <xzpelo8ii94.fsf@flood.ping.uio.no> <200110122330.f9CNU1u36917@earth.backplane.com> <xzpelo4r90f.fsf@flood.ping.uio.no> <200110152135.f9FLZpg56816@earth.backplane.com> <20011016172843.A469@nebula.cybercable.fr> <200110161618.f9GGIpM31430@apollo.backplane.com>

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Matthew Dillon wrote:
> :I think I'm experiencing the same problem as des.  After a bit of
> :uptime, or even better, after a big cvs update, I can see the system cpu
> :time of my -CURRENt box jumping from 0 to 50% (or more) every 30 seconds.
> :Of course, this also happens in single user mode.
> :
> :So I built a profiling kernel as explained and tried to catch this
> :happening.  The results of the profiling are attached.
> :
> :Hope this helps,
> :Maxime Henrion
> :...
> 
> :[4]     18.8    0.00        0.53       1         sync_fsync [4]
> :                0.09        0.30       1/1           ffs_sync [5]
> :                0.05        0.08       1/1           vfs_msync [11]
> 
> :-----------------------------------------------
> :
> :                0.09        0.30       1/1           sync_fsync [4]
> :[5]     14.0    0.09        0.30       1         ffs_sync [5]
> :                0.09        0.21       1/1           qsync [7]
> 
>     qsync()?  Quota sync?  Maxime, do you have quotas enabled?  DES,
>     do you have quotas enabled?
> 
>     It sure looks like qsync() is the responsible party in this
>     profile, and looking at the code I can see why.  It's an
>     insanely expensive procedure.  It's vget()ing and vput()ing every
>     single vnode in the vnode cache and doing other nasty things.

I do have quotas indeed.

Maxime
-- 
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