Date: Mon, 16 Oct 2006 14:09:29 -0400 From: Kris Kennaway <kris@obsecurity.org> To: Chris <chrcoluk@gmail.com>, OM@xor.obsecurity.org Cc: freebsd-performance@freebsd.org, Kris Kennaway <kris@obsecurity.org>, Eric Hodel <drbrain@segment7.net> Subject: Re: Help with improving mysql performance on 6.2PRE Message-ID: <20061016180928.GA28108@xor.obsecurity.org> In-Reply-To: <3aaaa3a0610161105m72d0b5d8y17bd1e1835a4d5d4@mail.gmail.com> 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> <3aaaa3a0610161105m72d0b5d8y17bd1e1835a4d5d4@mail.gmail.com>
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--Dxnq1zWXvFF0Q93v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 16, 2006 at 07:05:28PM +0100, Chris wrote: > 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 > > > > > >_______________________________________________ >=20 > 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. This is a very surprising and anomalous result. Can you please provide more details? kris --Dxnq1zWXvFF0Q93v Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFM8rYWry0BWjoQKURAu+lAKDW6+NqJeB3wdhKJ99kTwE083hK0wCgp5Rh bHyBdRLjoN9OOdYcOSkkK0k= =RzVY -----END PGP SIGNATURE----- --Dxnq1zWXvFF0Q93v--
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