From owner-freebsd-hackers@FreeBSD.ORG Wed Oct 3 03:30:04 2007 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EEBD516A417; Wed, 3 Oct 2007 03:30:04 +0000 (UTC) (envelope-from bright@elvis.mu.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.freebsd.org (Postfix) with ESMTP id E394613C455; Wed, 3 Oct 2007 03:30:04 +0000 (UTC) (envelope-from bright@elvis.mu.org) Received: by elvis.mu.org (Postfix, from userid 1192) id B82C31A4D7E; Tue, 2 Oct 2007 20:30:04 -0700 (PDT) Date: Tue, 2 Oct 2007 20:30:04 -0700 From: Alfred Perlstein To: Kip Macy Message-ID: <20071003033004.GS31826@elvis.mu.org> References: <20071003015231.GJ31826@elvis.mu.org> <20071003025418.GN31826@elvis.mu.org> <20071003030943.GQ31826@elvis.mu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i Cc: Daniel Eischen , hackers@freebsd.org Subject: Re: Critical Sections for userland. X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Oct 2007 03:30:05 -0000 * Kip Macy [071002 20:24] wrote: > See /sys/priority.h realtime is right below ithreads in terms of > priority. One of the big motivations for gang scheduling and part of > the reason why SMP guests often perform poorly is that apps / VMs > don't scale well if they're descheduled from the cpu while holding a > lock. Yes, exactly the problem, it sucks when process A on CPU 1 runs out of quantum while holding a lock that a runner on CPU 2 wants. -- - Alfred Perlstein