Re: mysql scaling questions

Gergely CZUCZY wrote:
> On Sun, Dec 30, 2007 at 02:35:56PM +0100, Kris Kennaway
wrote:
>> Gergely CZUCZY wrote:
>>
>>>> I appreciate that you might be constrained
by local requirements, but it's really not meaningful to
compare different mysql versions 
>>>> if your goal is to study OS performance.
>>> It'd be a PITA to install the both versions.
Maybe now, that the ports freeze is over, i can
>>> do something. But honestly, every mysql version
was faster on linux, than eny on FreeBSD,
>>> even the .22 one was faster. We start work on
Jan02, I will see what can I do.
>> Regardless, we need a stable baseline to compare
to.
> Cannot do it sooner then january. Any recommended
versions?

Either 5.0.45 on both, or 5.0.51 on both, please.

>> Still waiting for your sysbench command lines 
> There were 2 scripts and a sources file with options:
> 
> basicall that's everything. I know it's a but complex,
but this was all behind it.

OK, that was very important since you're changing defaults.

It looks like myisam is doing huge numbers of concurrent
reads of the 
same file which is running into exclusive locking in the
kernel (vnode 
interlock and lockbuilder mtxpool).  Does it not do any
caching of the 
data in userspace but relies on querying into the kernel
every time? 
innodb doesn't have this behaviour.

Kris

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ON SUN, DEC 30, 2007 AT 03:08:28PM +0100, KRIS KENNAWAY
WROTE:
> GERGELY CZUCZY WROTE:
> >ON SUN, DEC 30, 2007 AT 02:35:56PM +0100, KRIS
KENNAWAY WROTE:
> >>GERGELY CZUCZY WROTE:
> >>
> >>>>I APPRECIATE THAT YOU MIGHT BE
CONSTRAINED BY LOCAL REQUIREMENTS, BUT IT'S REALLY NOT
MEANINGFUL TO COMPARE DIFFERENT MYSQL 
> >>>>VERSIONS IF YOUR GOAL IS TO STUDY OS
PERFORMANCE.
> >>>IT'D BE A PITA TO INSTALL THE BOTH
VERSIONS. MAYBE NOW, THAT THE PORTS FREEZE IS OVER, I CAN
> >>>DO SOMETHING. BUT HONESTLY, EVERY MYSQL
VERSION WAS FASTER ON LINUX, THAN ENY ON FREEBSD,
> >>>EVEN THE .22 ONE WAS FASTER. WE START WORK
ON JAN02, I WILL SEE WHAT CAN I DO.
> >>REGARDLESS, WE NEED A STABLE BASELINE TO
COMPARE TO.
> >CANNOT DO IT SOONER THEN JANUARY. ANY RECOMMENDED
VERSIONS?
> 
> EITHER 5.0.45 ON BOTH, OR 5.0.51 ON BOTH, PLEASE.
ACK.

> >>STILL WAITING FOR YOUR SYSBENCH COMMAND LINES

> >THERE WERE 2 SCRIPTS AND A SOURCES FILE WITH
OPTIONS:
> >BASICALL THAT'S EVERYTHING. I KNOW IT'S A BUT
COMPLEX, BUT THIS WAS ALL BEHIND IT.
> 
> OK, THAT WAS VERY IMPORTANT SINCE YOU'RE CHANGING
DEFAULTS.
FOR DIFFERENT CONFIGURATIONS, YES. BUT EVERY TEST IS
HETEROGENOUS.
> 
> IT LOOKS LIKE MYISAM IS DOING HUGE NUMBERS OF
CONCURRENT READS OF THE SAME FILE WHICH IS RUNNING INTO
EXCLUSIVE LOCKING IN THE KERNEL 
> (VNODE INTERLOCK AND LOCKBUILDER MTXPOOL).  DOES IT NOT
DO ANY CACHING OF THE DATA IN USERSPACE BUT RELIES ON
QUERYING INTO THE KERNEL 
> EVERY TIME? INNODB DOESN'T HAVE THIS BEHAVIOUR.
SORRY, BUT WAS THIS A RETHORICAL KIND OF QUESTION, OR WAS
THIS ADDRESSED TO ME? 
IF THE LATER, THEN HOW DO I FIND THIS OUT?

SINCERELY,

GERGELY CZUCZY
MAILTO: GERGELY.CZUCZYHARMLESS.HU

-- 
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