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Date: Mon, 19 Nov 2007 19:24:18 +0100
From: Kris Kennaway <kris@FreeBSD.org>
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To: Alexey Popov <lol@chistydom.ru>
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Cc: freebsd-stable@freebsd.org, Robert Watson <rwatson@FreeBSD.org>
Subject: Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD
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Alexey Popov wrote:
> Hi.
> 
> Robert Watson wrote:
>>> I tried SCHED_ULE, but got no difference:
>> Did you see no change in throughput, or no change in reported CPU use?
> No significant changes.
> 
>> We should probably take this thread to performance@ and get Kris 
>> involved.  He may be interested in trying to reproduce your workload 
>> in our testbed so we can perform measurements of our own, as well as 
>> getting you to provide profiling information.  One of the things we'd 
>> most like to have are nice potted benchmarks for real-world workloads, 
>> as that allows us to easily replay them, perform measurements, 
>> optimize, etc.
> I can provide all profiling or configuration information you ask for. 
> Except I can't provide PHP site source codes.
> 
> Now I'm in situation that I can't install FreeBSD on all new servers 
> because they are all based on 2xquad-core processors and I can't be sure 
> it would work good.

Running mutex profiling for e.g. 1 minute of representative load would 
be a useful starting point, as well as hwpmc profiling for the same 
duration.

My guess is that you're hitting contention in the TCP send path, but I 
missed the start of this conversation so I don't know what problems you 
are seeing.

Kris