From owner-freebsd-arch Wed May 24 15:56: 7 2000 Delivered-To: freebsd-arch@freebsd.org Received: from berserker.bsdi.com (berserker.twistedbit.com [199.79.183.1]) by hub.freebsd.org (Postfix) with ESMTP id DA3C637B636 for ; Wed, 24 May 2000 15:56:04 -0700 (PDT) (envelope-from cp@berserker.bsdi.com) Received: from berserker.bsdi.com (cp@[127.0.0.1]) by berserker.bsdi.com (8.9.3/8.9.3) with ESMTP id QAA14414 for ; Wed, 24 May 2000 16:56:04 -0600 (MDT) Message-Id: <200005242256.QAA14414@berserker.bsdi.com> To: arch@freebsd.org Subject: Re: Preemptive kernel on older X86 hardware From: Chuck Paterson Date: Wed, 24 May 2000 16:56:03 -0600 Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I should point out that what is being proposed here is a totally different model for kernel protection. SPLS go away totally and are replaced by locks, almost always mutexs. Mutexs protect data, not a thread of control. Saying that a SPL is replaced by a mutex is still kind of misleading because the model is so different. I would like to claim that this change is totally performance neutral, but I don't know that for sure, and never will until the work is done. It is however very close to neutral. I can say that a kernel build that takes approximately 30 minutes on an admittedly slow uniprocessor took about 10 seconds less with the SMPng kernel. A build is obviously heavy user time. Chuck To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message