Date: Wed, 18 Apr 2001 09:32:12 +0930 From: Greg Lehey <grog@lemis.com> To: Alfred Perlstein <bright@wintelcom.net> Cc: Matt Dillon <dillon@earth.backplane.com>, "Justin T. Gibbs" <gibbs@scsiguy.com>, Doug Barton <DougB@DougBarton.net>, "current @ freebsd . org" <current@FreeBSD.ORG> Subject: Kernel preemption, yes or no? (was: Filesystem gets a huge performance boost) Message-ID: <20010418093212.A80877@wantadilla.lemis.com> In-Reply-To: <20010417011957.W976@fw.wintelcom.net>; from bright@wintelcom.net on Tue, Apr 17, 2001 at 01:19:57AM -0700 References: <200104160259.f3G2xqs06321@aslan.scsiguy.com> <200104160616.f3G6GI973782@earth.backplane.com> <20010417011957.W976@fw.wintelcom.net>
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On Tuesday, 17 April 2001 at 1:19:57 -0700, Alfred Perlstein wrote: > * Matt Dillon <dillon@earth.backplane.com> [010415 23:16] wrote: >> >> For example, all this work on a preemptive >> kernel is just insane. Our entire kernel is built on the concept of >> not being preemptable except by interrupts. We virtually guarentee >> years of instability and bugs leaking out of the woodwork by trying to >> make it preemptable, and the performance gain we get for that pain >> is going to be zilch. Nada. Nothing. > > Pre-emption is mearly a side effect of a mutex'd kernel. > > The actual gains are in terms of parallel execution internally. > Meaning if we happen to copyin() a 4 meg buffer we can allow more > than one process to be completing some sort of work inside the > kernel other than spinning on the giant lock. *sigh* Couldn't you have changed the subject line when discussing something of this importance? Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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