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Date: Sun, 23 May 2004 16:11:22 -0400 (EDT)
From: Daniel Eischen <eischen@vigrid.com>
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To: JG <amd64list@jpgsworld.com>
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cc: freebsd-threads@freebsd.org
Subject: Re: Why is MySQL nearly twice as fast on Linux?
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On Sun, 23 May 2004, JG wrote:

> At 08:09 PM 5/23/2004 +0300, you wrote:
> >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=20
> >supersmack on fairly old machine (800MHz dual pentium) I get ~30 active=
=20
> >mysql threads using CPU between 1.5% and 3.5%.
>=20
> You mean where I have the 3 instances of mysqld running in top?  You have=
=20
> ~30 instances?
>=20
> Why would your box use more? Is there any configuration or flag in mysql=
=20
> that would cause this?
>=20
> How was your mysql compiled? What version of FreeBSD are you running?
>=20
> >I would suspect the test is limited by context switch and syscall=20
> >overhead. With the old machine I see >70000 syscalls and >20000 context=
=20
> >switches a second. So I suspect FreeBSD syscall overhead compared to lin=
ux=20
> >must be higher. Mysql also asks for time repeatedly so make sure you are=
=20
> >running ACPI timecounters. (don=B4t know if they are available on AMD64)=
=2E
>=20
> I know that this FreeBSD/AMD64 reports that it is using ACPI... how do I=
=20
> find out if its using timecounters, or using them properly?

Doesn't Linux use HZ=3D1000 by default now and FreeBSD is still at HZ=3D100=
?
Could that affect anything?

--=20
Dan Eischen