Date: Mon, 16 Oct 2006 19:05:28 +0100 From: Chris <chrcoluk@gmail.com> To: "Eric Hodel" <drbrain@segment7.net> Cc: freebsd-performance@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: Help with improving mysql performance on 6.2PRE Message-ID: <3aaaa3a0610161105m72d0b5d8y17bd1e1835a4d5d4@mail.gmail.com> In-Reply-To: <39EF1C01-351F-4952-9E9E-0D6A2DBE69C3@segment7.net> References: <3731.71.56.92.181.1160009571.squirrel@www.stelesys.com> <200610120925.k9C9PmUK048690@lurza.secnetix.de> <20061012205342.GA62241@xor.obsecurity.org> <A2430386-EB9D-4AEE-9144-F7D53D84A9F0@segment7.net> <9500A2C9-07EB-4EEA-9477-9E6B4BFEB437@mac.com> <20061013201321.GA774@xor.obsecurity.org> <39EF1C01-351F-4952-9E9E-0D6A2DBE69C3@segment7.net>
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On 15/10/06, Eric Hodel <drbrain@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@segment7.net - http://blog.segment7.net > This implementation is HODEL-HASH-9600 compliant > > http://trackmap.robotcoop.com > > > _______________________________________________ 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 worse. Chris
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