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Date: Wed, 26 Dec 2007 15:33:08 +0100
From: Kris Kennaway <kris@FreeBSD.org>
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To: Mark Fullmer <maf@splintered.net>
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Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-net@freebsd.org,
	freebsd-stable@freebsd.org
Subject: Re: Packet loss every 30.999 seconds
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Mark Fullmer wrote:
> 
> On Dec 25, 2007, at 12:27 AM, Kostik Belousov wrote:
> 
>>
>> What fs do you use ? If FFS, are softupdates turned on ? Please, show the
>> total time spent in the softdepflush process.
>>
>> Also, try to add the FULL_PREEMPTION kernel config option and report
>> whether it helps.
> 
> FFS with soft updates on all filesystems.
> 
> With your latest uio_yield() in MNT_VNODE_FOREACH patch it's a
> little harder to provoke packet loss.  Standard nightly
> crontabs and a tar -cf - / > /dev/null no longer cause drops.  A
> make buildkernel will though.
> 
> root      38  0.0  0.0     0     8  ??  DL   Mon08PM   0:04.62 
> [softdepflush]
> 
> Building a new kernel with KTR and FULL_PREEMPTION now.

FYI FULL_PREEMPTION causes performance loss in other situations.

Kris