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Date:      Fri, 30 Nov 2007 10:28:24 +0100
From:      Kris Kennaway <kris@FreeBSD.org>
To:        Alexey Popov <lol@chistydom.ru>
Cc:        Attilio Rao <attilio@freebsd.org>, freebsd-stable@freebsd.org
Subject:   Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD
Message-ID:  <474FD7B8.7000003@FreeBSD.org>
In-Reply-To: <474FD2BF.606@chistydom.ru>
References:  <4741905E.8050300@chistydom.ru>	<fhs3s5$knj$1@ger.gmane.org>	<47419AB3.5030008@chistydom.ru>	<fhs7hp$2es$2@ger.gmane.org> <4741A7DA.2050706@chistydom.ru> <4741DA15.9000308@FreeBSD.org> <47429DB8.7040504@chistydom.ru> <4742ADFE.40902@FreeBSD.org> <4742C46A.1060701@chistydom.ru> <47432F77.3030606@FreeBSD.org> <474339E9.4080301@FreeBSD.org> <4743629B.9090408@FreeBSD.org> <47456B71.5040205@chistydom.ru> <4745E5B3.6060200@FreeBSD.org> <47468165.5010906@chistydom.ru> <4746B21F.7050906@FreeBSD.org> <4746BD92.6000204@chistydom.ru> <474F12AE.7050808@FreeBSD.org> <474FD2BF.606@chistydom.ru>

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Alexey Popov wrote:
> Hi
> 
> Kris Kennaway wrote:
>> One more patch which may or may not help is:
>>
>>   http://www.freebsd.org/~jhb/patches/namei_rwlock.patch
>>
>> (may also require porting since it was against an older version of 
>> 7.0-CURRENT).  When I have tested this in the past it was a 
>> performance loss for reasons that I think I understand (basically, it 
>> is locally a performance improvement for the name cache but also 
>> requires a fixed lockmgr to avoid an overall performance loss), but I 
>> don't remember if I tested it in conjunction with the lockmgr patch.
> This patch doesn't apply to 7-STABLE because /sys/kern/vfs_cache.c was 
> changed significanly since rev. 1.108. I tried to patch it manually but 
> don't know what to do with cache_lookup() changes.

OK, I am about to go on vacation so I am not able to help with either of 
these things.

Kris

> 
>>>> There are patches you need to enable it on woodcrest.  They are in 
>>>> my p4 branch (kris-contention) but I don't have time right now to 
>>>> extract them.
>>> I think it would be very useful because I can't see any other ways to 
>>> profile FreeBSD on the modern many-cores machines.
>>
>> You can extract the changeset from my branch via 
>> http://perforce.freebsd.org.  Unfortunately I don't have time to do it 
>> myself.
> I'll try it if it does not also need porting.
> 
> With best regards,
> Alexey Popov
> 
> 




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