Date: Tue, 13 Dec 2005 15:42:18 +0200 From: Peter Pentchev <roam@ringlet.net> To: "Jin Guojun \[VFFS\]" <j_guojun@lbl.gov> Cc: freebsd-performance@freebsd.org, David Xu <davidxu@freebsd.org>, "Gustavo A. Baratto" <gbaratto@superb.net> Subject: Re: mysql benchmarks Message-ID: <20051213134218.GB1142@straylight.m.ringlet.net> In-Reply-To: <439A5411.8090005@lbl.gov> References: <032801c5fd32$df28c3b0$6400a8c0@garrincha> <439A4301.5030404@freebsd.org> <439A5411.8090005@lbl.gov>
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--JYK4vJDZwFMowpUq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Dec 09, 2005 at 08:05:37PM -0800, Jin Guojun [VFFS] wrote: > David Xu wrote: >=20 > >Gustavo A. Baratto wrote: > > > >>Since the last post just had freebsd numbers, I'm re-posting it=20 > >>including > >>Linux as well. Both linux and freebsd numbers were taken from the=20 > >>same box: > > > > > >... > > > >Can you try TSC timer on FreeBSD ? someone reported that using TSC > >timer boosts performance of super-smack significantly. > > > >David Xu >=20 > "TSC" can be a few 100 times faster than gettimeofday(), but one needs=20 > to know > how to calibrate and convert it to timer because TSC is counter, not time= r. >=20 > Also, if FreeBSD uses TSC to compare with Linux using gettimeofday, > it does not sound a fun. > gettimeofday is a very expensive function on all systems. > http://dsd.lbl.gov/DIDC/papers/imc-2003.pdf > tells how much it costs on some common systems, especially FreeBSD and=20 > Linux. >=20 > So, if both systems use gettimeofday, then slow may be somewhere else. Errrr... I think David might have meant that the original poster should simply set kern.timecounter.hardware to 'TSC', not i8254 or something else. This would not change whether MySQL uses gettimefday() or not, it would simply change the in-kernel method of obtaining the actual time of day - at least that's how I understand it :) G'luck, Peter --=20 Peter Pentchev roam@ringlet.net roam@cnsys.bg roam@FreeBSD.org PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553 This sentence every third, but it still comprehensible. --JYK4vJDZwFMowpUq Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDns+67Ri2jRYZRVMRAgcmAKCSsMi3xo3eqLACOLMhFNJzDKWxAQCgmITd eexqWDLIVniS4tH+MTEXDao= =hZFB -----END PGP SIGNATURE----- --JYK4vJDZwFMowpUq--
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