Date: Fri, 18 Jan 2002 22:35:36 -0800 From: Peter Wemm <peter@wemm.org> To: Alfred Perlstein <bright@mu.org> Cc: David Malone <dwmalone@walton.maths.tcd.ie>, Josef Grosch <jgrosch@mooseriver.com>, hackers@FreeBSD.ORG Subject: Re: [nicole@unixgirl.com: What is biord?] Message-ID: <20020119063536.EC5EE39EC@overcee.wemm.org> In-Reply-To: <20020116151549.O26067@elvis.mu.org>
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Alfred Perlstein wrote:
> * David Malone <dwmalone@walton.maths.tcd.ie> [020116 14:30] wrote:
> > On Wed, Jan 16, 2002 at 02:18:25PM -0800, Josef Grosch wrote:
> > > I have a mysql database that seems slow and when looking at it in top it
> > > always seems to be in a state of biord
> > > What the heck is biord I can't find this anywere
> >
> > 22:21:gonzo 3% fgrep biord /usr/src/sys/kern/*
> > /usr/src/sys/kern/vfs_bio.c: tsleep(&bp->b_xflags, PRIBIO, "bior
d", 0);
> > /usr/src/sys/kern/vfs_bio.c: tsleep(bp, PRIBIO, "biord",
0);
> >
> > If you have a look at the code, in vfs_bio.c around these lines,
> > you'll see it is to do with waiting for buffers to be read or
> > written. Basically it means that the database is spending alot
> > of its time waiting for the disk to catch up.
>
> If you compile mysql using the linuxthreads port instead of freebsd
> native threads you _might_ see a performance improvement.
>
> -Alfred
If mysql is blocking on bioread, then it is stalling the entire thread
engine when one hits disk IO. Using the linuxthreads port cant help but
make it work better / more smoothly.. especially if there are multiple
clients.
Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5
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