Date: Tue, 16 Oct 2001 09:18:51 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Maxime Henrion <mux@qualys.com>, Dag-Erling Smorgrav <des@ofug.org> Cc: cvs-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/vm vnode_pager.c Message-ID: <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>
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: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.
-Matt
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