FreeBSD MySQL still WAY slower than Linux

[Guy Helmer]

Steve Roome wrote:

>We're using mostly:
>
>  5.4-STABLE FreeBSD 5.4-STABLE #0: Mon Jun 6 12:22:18 BST 2005
>
>This is on a Dell PowerEdge 2850. (2 * 2.8 GHz Xeons, 4GB ram, disks),
>we've been keeping up with stable because supposedly all these new
>fixes to threading will help us out here.
>
>We're trying to get FreeBSD to perform reasonably well, in comparison
>to Linux, or even what we should expect to see. We're getting about
>half the performance we get from gentoo on the same application
>(mysql).
>
>The discussion on the 'freebsd-threads' mailing list about a year ago 
>seems to match our experiences nowadays pretty well:
>
>	http://lists.freebsd.org/pipermail/freebsd-threads/2004-May/002002.html
>
>Nothing much seems to have changed, although lots of people claim that
>FreeBSD 5.x is now fine, it doesn't seem to be.
>
>Here's a rough breakdown of the sort of performance we're seeing, this
>is the default select-key super-smack but setup for innodb rather than
>myisam.
>
>  
>
>>Using the simple 'select-key.smack' Super-Smack benchmark (50 clients 
>>with 1000 runs each):
>>
>>OS          CPUs    Build       Threading        Kqueries/sec
>>-------------------------------------------------------------
>>FreeBSD      1      Pro         KSE                  10.6
>>FreeBSD      1      Pro         libthr               10.6
>>FreeBSD      2      Pro         libthr               14.4
>>FreeBSD      2      Source      libthr               14.5
>>FreeBSD      2      Source      KSE/P (static)       15.7
>>FreeBSD      2      Source      KSE/P (dynamic)      15.8
>>FreeBSD      2      Source      KSE/S (dynamic)      15.8
>>FreeBSD      2      Pro         KSE                  15.9
>>FreeBSD      2      Source      LinuxThreads         17.7
>>Gentoo       2      Source      NPTL                 34.0  !!
>>
>>(KSE/P = KSE with Process Scope Threading, KSE/S = KSE with System 
>>Scope Threading)
>>    
>>
>
Quick ideas:

Have you tried a kernel with PREEMPTION enabled?  I haven't quantified 
the effect, but it's improved performance in some situations.

Have you tried increasing vfs.read_max?

Guy

-- 
Guy Helmer, Ph.D., Principal System Architect, Palisade Systems, Inc.
ghelmer at palisadesys.com
http://www.palisadesys.com/~ghelmer