Help with improving mysql performance on 6.2PRE
kris at obsecurity.org
Mon Oct 16 18:10:37 UTC 2006
On Mon, Oct 16, 2006 at 07:05:28PM +0100, Chris wrote:
> On 15/10/06, Eric Hodel <drbrain at segment7.net> wrote:
> >On Oct 13, 2006, at 1:13 PM, Kris Kennaway wrote:
> >> On Fri, Oct 13, 2006 at 11:49:04AM -0700, Chuck Swiger wrote:
> >>> On Oct 13, 2006, at 11:26 AM, Eric Hodel wrote:
> >>>>>> Or did that change recently?
> >>>>> It's only on certain systems, apparently.
> >>>> Is there a list of systems where it is safe to use the TSC with
> >>>> SMP? Or some script we can run?
> >>> The problem of the TSC clocks getting out of sync affects pretty much
> >>> all AMD X2 dual-core CPUs, as well as the older 32-bit Althon MP
> >>> CPUs; the Intel Xeon and Core Duo CPUs seem to do a lot better,
> >>> although older Intel CPUs have also been reported to show problems
> >>> with the TSC.
> >> Beyond that, just see if it works ;-)
> >How "safe" is it to switch timecounters? I don't have a spare
> >machine to test on...
> > From my readings on switching the TSC over the past several months I
> >think that if it doesn't work I'll see is ntpd adjusting my system
> >clock more often (or falling out of sync). I don't know if this will
> >corrupt mysql while its running though (which is my fear).
> >FWIW I have a "Dual Core AMD Opteron(tm) Processor 270".
> >Eric Hodel - drbrain at segment7.net - http://blog.segment7.net
> >This implementation is HODEL-HASH-9600 compliant
> I switched from the default timer to TSC on a dual xeon setup and my
> loads instantly went up with mysql lagging, so in my case it was much
This is a very surprising and anomalous result. Can you please
provide more details?
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