Subject: Re: nfsds using all CPU, STATE = "vnlock"
To: Johan A. van Zanten <firstname.lastname@example.org>
From: Bill Stouder-Studenmund <email@example.com>
Date: 10/14/2007 16:30:55
Content-Type: text/plain; charset=us-ascii
On Sat, Oct 13, 2007 at 05:55:04PM -0500, Johan A. van Zanten wrote:
> I have a 2.4 Ghz Pentium 4 running NetBSD 3.1-STABLE.
> Boot disk is SCSI, but i have two Maxtor 7H500F0 500 GB SATA data-only
> drives that i serve out over NFS. They only have one file system each, and
> it is "type ffs," but it is mounted with softdeps.
> I recently got a Mac mini (running MacOS 10.4) and an EyeTV 250 plus (
> http://www.elgato.com/index.php?file=3Dproducts_eyetv250na ) to do record
> broadcast HD programs for enjoyment on my on schedule. The data files for
> these programs seem to work out to be about 100 MB / minute recorded, or 6
> GB for an hour program. I guess this comes out to be about 1.6 MB/s
> sustained I/O.
> On a few occasions, i've seen the CPU use on the pentium4 spike to 100%,
> and it's all being consumed (evenly) by the four nfsds, system not user
> time. They are mostly in the "vnlock" state. When functioning normally
> (even when writing the same volume and type of data), they seem to use
> less than ~0.30% of the CPU each.
Pay attention to the ones not in "vnlock". Processes in "vnlock" are=20
sleeping, waiting on a vnode lock. They thus aren't directly consuming=20
CPU. You really want to know what the vnode lock holder is doing while=20
this is happening.
I'm going to blame softdeps. Can you try things w/o them?
> The system seems to recover, but i have noticed some of the recorded
> programs have lost substantial chunks of data, though that could
> also be due to many other factors, such as antenna reception.
Some sort of cleanup is happening and gobbling lots of CPU.
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