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Date:      Thu, 24 Jun 1999 12:34:06 -0700
From:      Mike Smith <mike@smith.net.au>
To:        Dan Moschuk <dan@trinsec.com>
Cc:        hackers@freebsd.org
Subject:   Re: Beating system usage down 
Message-ID:  <199906241934.MAA01020@dingo.cdrom.com>
In-Reply-To: Your message of "Thu, 24 Jun 1999 12:18:16 EDT." <19990624121816.A17448@trinsec.com> 

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Just for those that have been following the benchmarking thread, this 
is exactly the same symptom set that FreeBSD demonstrates when loaded 
by WebBench.  The gotcha here is, again, the giant kernel lock.

> Greetings,
> 
> A machine that I hold very close under my wing has been very contently
> chugging along for the last few months with practically no idle processor.
> However, I noticed that the CPUs are spinning a lot of cycles in the
> system area. 
> 
> CPU states:  5.5% user,  0.0% nice, 88.9% system,  4.0% interrupt,  1.6% idle
> 
> First, some background.
> 
> The machine is a Dual P2-450 with 1GB of RAM.  It runs apache, and currently
> handles 90 hits a second, with each of those hits spawning various CGIs 
> (one per hit) that completes in under a second.
> 
> My first theory was that the kernel was uselessly spinning in various record
> locks via fcntl().  However, as a test I removed all file locking from the
> various CGIs and noticed no change in the system usage.  My second theory
> was the overhead with the SMP code.  So, I removed it from the kernel and
> ran a single CPU box for a few minutes.  The system usage went down to 
> around 60%, but the system was noticeably slower.
> 
> Any ideas?
> 
> 
> Regards,
> 
> Dan
> 
> 
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-- 
\\  The mind's the standard       \\  Mike Smith
\\  of the man.                   \\  msmith@freebsd.org
\\    -- Joseph Merrick           \\  msmith@cdrom.com




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