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Date: Mon, 4 Jul 2005 12:02:39 -0500
From: Dan Nelson <dnelson@allantgroup.com>
To: Peter Edwards <peadar.edwards@gmail.com>
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Cc: Peter Edwards <peadar@freebsd.org>, arch@freebsd.org,
	Robert Watson <rwatson@freebsd.org>
Subject: Re: ktrace and KTR_DROP
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In the last episode (Jul 03), Peter Edwards said:
> On 7/1/05, Robert Watson <rwatson@freebsd.org> wrote:
> > There are two cases where I really run into problems with the
> > current model:
> > 
> > (1) When I'm interacting with a slow file system, such as NFS over
> >      100mbps, I will always lose records, because it doesn't take
> >      long for the process to get quite ahead of the write-behind.
> 
> It doesn't even need NFS: syscall throughput is much better than I/O
> throughput :-)

BTW, I often see dropped records even when tracing to md-backed /tmp.
Raising kern.ktrace.request_pool from 100 to 1000 helps but does not
eliminate drops.

-- 
	Dan Nelson
	dnelson@allantgroup.com