2 x quad-core system is slower that 2 x dual core on FreeBSD

[Krassimir Slavchev]

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Robert Watson wrote:
> 
> On Tue, 4 Dec 2007, Krassimir Slavchev wrote:
> 
>>>> Evidence in-hand seems to suggest that 8 core systems work very well
>>>> for most users, and reflect a significant performance increase with
>>>> 7.0 over previous FreeBSD releases.
>>>
>>> I disagree with that. Heavily loaded Apache, MySQL, Postgres does not
>>> work well.
>>
>> There is another report for such problems:
>>
>> http://blog.insidesystems.net/articles/2007/04/09/what-did-i-do-wrong
> 
> A casual reading suggests that this article is about FreeBSD 6.2, and
> not FreeBSD 7.0.  Am I misreading?

No, But these tests can be performed on FreeBSD 7.0 4/8 core systems.

> 
> Robert N M Watson
> Computer Laboratory
> University of Cambridge
> 
>>
>>>
>>>>>>  The right path forwawrd at this point is to diagnosis the problems
>>>>>> and work on fixing them in 8-CURRENT, and assuming they are not
>>>>>> highly disruptive, MFC them for FreeBSD 7.1.
>>>>>
>>>>> I believe at least the bug with lockmgr contention should be fixed
>>>>> before release.
>>>> Could you point me at the specific proposed change in question?  I
>>>> don't think I've seen it come across re@ as a potential merge
>>>> request.  Changing locking primitives close to a release is, FYI, a
>>>> risky business, as while it may improve performance in specific cases,
>>>> we may not have a lot of information about more general cases.  We
>>>> also risk opening up previously nascent race conditions in lock
>>>> consumers.
>>> Kris sent me proof of concept patch that helped much against high
>>> lockmgr contention. After applying this patch 8-core server become
>>> faster that 4-core. But, again, it's still slower than Linux.
>>>
>>> Here's the patch:
>>> http://lists.freebsd.org/pipermail/freebsd-stable/2007-November/038449.html
>>>
>>>
>>> Here's Kris saying that it helps:
>>> http://lists.freebsd.org/pipermail/freebsd-stable/2007-November/038672.html
>>>
>>>
>>> I'm not sure it will help to MySQL and Prostgres, but symptoms are
>>> mostly identical.
>>>
>>> With best regards,
>>> Alexey Popov
>>> _______________________________________________
>>> freebsd-stable at freebsd.org mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-stable
>>> To unsubscribe, send any mail to
>>> "freebsd-stable-unsubscribe at freebsd.org"
>>>
>>
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