From owner-freebsd-questions  Wed Sep 22  6:12:44 1999
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Date: Wed, 22 Sep 1999 15:10:00 +0200
From: Dirk Froemberg <dirk@FreeBSD.ORG>
To: Dan Nelson <dnelson@emsphone.com>
Cc: "Ronald F. Guilmette" <rfg@monkeys.com>, ports@FreeBSD.ORG,
	questions@FreeBSD.ORG
Subject: Re: mysql-server-3.22.25 install botch (pthread_attr_setschedparam?)
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References: <19990919230055.E42360@physik.TU-Berlin.DE> <27137.937789692@monkeys.com> <19990921222033.A96951@physik.TU-Berlin.DE> <19990921162521.A4053@dan.emsphone.com>
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In-Reply-To: <19990921162521.A4053@dan.emsphone.com>; from Dan Nelson on Tue, Sep 21, 1999 at 04:25:21PM -0500
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Hi Dan, hi Ronald!

On Tue, Sep 21, 1999 at 04:25:21PM -0500, Dan Nelson wrote:
> In the last episode (Sep 21), Dirk Froemberg said:
> > > I hope that it is apparent what I am really asking here.  If I run
> > > mySQL on a multiprocessor system that is running FreeBSD, will it
> > > actually be able to make use of more than one processor at a time
> > > on that system? Does the FreeBSD kernel provide adequate support
> > > for this?
> > 
> > Yes, definitly. FreeBSD-SMP scales very well (see
> > http://www.freebsd.org/~fsmp/SMP/akgraph-a/graph1.html for details).
> > 
> > And yes, MySQL will benefit from more than one processor. That's what
> > threads support is for. 8-)
> 
> Are you sure?  I thought threads support was to avoid the context
> switch of a full process, mainly because Windows processes are so
> inefficient.
> 
> AFAIK, user-level threads are implemented as a single process, and use
> setitimer() to switch threads.  All threads will run on one CPU, so SMP
> won't help much at all.

Oh damned, you're right!

I remember some tests with MySQL on a SMP machine. It must have
been the Solaris machine taking benefit of two processors.

So the mysql-port on FreeBSD does _NOT_ gain any speed on a SMP machine.

Thanks for the correction and sorry for the confusion.

	Regards Dirk

-- 
Dirk Froemberg


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