Date: Wed, 27 Feb 2002 14:40:14 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Julian Elischer <julian@elischer.org> Cc: Bosko Milekic <bmilekic@unixdaemons.com>, Jeff Roberson <jroberson@chesapeake.net>, arch@FreeBSD.ORG Subject: Re: Slab allocator Message-ID: <3C7D604E.45D0D959@mindspring.com> References: <Pine.BSF.4.21.0202271333340.97278-100000@InterJet.elischer.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Julian Elischer wrote: > On Wed, 27 Feb 2002, Terry Lambert wrote: > > This is ridiculous: > > > > 1) Kernel preemption should *never* result in CPU > > migration. > > why not? > > "should not"" or "can't"? > "shouldn't" can be argued either way, > and "can't" is easily proven false. Should not. A kernel thread should run to completion on a single CPU. Note that this applies to kernel threads, not kernel processes. A kernel thread is a backing object -- a context -- borrowed for a short term operation. Any migration of these things will, by definition, result in cache busting. There's little good that can come from such migration. > > 2) Allocations at interrupt level are an extreme > > special case, and should be handled as a special > > case, so as not to damage the performance of the > > common case. > > that's a whole different (design) issue. Maybe. It is none the less true that the set of things that can happen at any time is much larger than the set of things which are permitted to happen at interrupt, and great care should be taken when increasing the size of the latter set. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3C7D604E.45D0D959>