FreeBSD MySQL still WAY slower than Linux

[Mark Kirkwood]

Michael Schuh wrote:
>
> 
> My results was that RELENG_5 is half as RELENG_4 fast by disk-access
> (ata-related).
> 
> I have seen that RELENG_5 with GENERIC Kernel and only modified option HZ=2000.
> 
> the spread begind with Gentoo (mentoided from me as the slowest, but
> errare humanum est)
> 
> Gentoo : 100% time consumption
> RELENG_4: 67% time consumtion
> DrangonFly Rel1.2 69-72% time consumption (i think preemtion)
> RELENG_5 134% time consumtion
> 
> these tests are made on physically the same Hardware (real, not equal
> system, same system, same disk, same RAM) with the command:
> 
> # cd /; /usr/bin/time dd if=/dev/zero bs=1024 count=1024k of=zerofile;
> 
> 

You have shown that sequential IO is slower in RELENG_5 (I think others 
have observed this also - check out Google)...However, random IO is 
often more important for databases, and RELENG_5 can be faster than 
RELENG_4 (try out iozone, it makes testing this easy).

Also note that if your operating systems are installed in different 
parts of the same disk, then this will effect your results too - as some 
parts are faster than others.

With respect to Mysql performance, I would suspect threading or 
threading/kernel interaction as the culprit. (That reminds me, I don't 
recall seeing the original poster re-doing the tests with 6.0-CURRENT - 
that would be interesting).

cheers

Mark