Date: Sun, 23 May 2004 20:09:50 +0300 From: Petri Helenius <pete@he.iki.fi> To: JG <amd64list@jpgsworld.com> Cc: freebsd-threads@freebsd.org Subject: Re: Why is MySQL nearly twice as fast on Linux? Message-ID: <40B0DADE.1070605@he.iki.fi> In-Reply-To: <5.2.0.9.2.20040523090659.01628af8@mail.ojoink.com> References: <5.2.0.9.2.20040522135338.0158cc50@mail.ojoink.com> <5.2.0.9.2.20040522100318.01598f50@mail.ojoink.com> <5.2.0.9.2.20040522052606.0156fd70@mail.ojoink.com> <5.2.0.9.2.20040521154458.01627688@127.0.0.1> <5.2.0.9.2.20040521154458.01627688@127.0.0.1> <5.2.0.9.2.20040522052606.0156fd70@mail.ojoink.com> <5.2.0.9.2.20040522100318.01598f50@mail.ojoink.com> <5.2.0.9.2.20040522135338.0158cc50@mail.ojoink.com> <5.2.0.9.2.20040523090659.01628af8@mail.ojoink.com>
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JG wrote: > > > > I am just a layman here, but what does this mean? > You seem to have a very small number of active threads. When I tried supersmack on fairly old machine (800MHz dual pentium) I get ~30 active mysql threads using CPU between 1.5% and 3.5%. I would suspect the test is limited by context switch and syscall overhead. With the old machine I see >70000 syscalls and >20000 context switches a second. So I suspect FreeBSD syscall overhead compared to linux must be higher. Mysql also asks for time repeatedly so make sure you are running ACPI timecounters. (donīt know if they are available on AMD64). With the old machine I got 1360 qps for the select test. (although itīs not idle, but doing light other work) Pete
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