From owner-freebsd-current@FreeBSD.ORG Sat May 29 18:09:04 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EB86616A4CE for ; Sat, 29 May 2004 18:09:04 -0700 (PDT) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9D3DA43D2D for ; Sat, 29 May 2004 18:09:04 -0700 (PDT) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.12.11/8.12.11) with ESMTP id i4U18LO3030446; Sat, 29 May 2004 21:08:21 -0400 (EDT) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)i4U18LYH030443; Sat, 29 May 2004 21:08:21 -0400 (EDT) (envelope-from robert@fledge.watson.org) Date: Sat, 29 May 2004 21:08:21 -0400 (EDT) From: Robert Watson X-Sender: robert@fledge.watson.org To: "Marc G. Fournier" In-Reply-To: <20040529203815.G907@ganymede.hub.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-current@freebsd.org Subject: Re: SCHED_BSD vs SCHED_ULE ... X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 May 2004 01:09:05 -0000 On Sat, 29 May 2004, Marc G. Fournier wrote: > Is there a circumstance where the older SCHED is better then ULE? Yes. I've noticed differing performance properties based on a number of factors, including hardware variation and workload. I've also noticed a couple of bugs in ULE that I'm hoping Jeff Roberson gets a chance to fix at some point, including some issues with load balancing. > Or is the older one something that will eventually just be removed > altogether? > > If the older does have areas in which it is the better, are there any > docs comparing the two? Well, I think it's useful to keep around 4BSD even if only to use as a performance baseline for understanding where ULE is working better or worse. I don't know of any specific documents talking about relative merits: generally, I would consider if a bug if ULE is consistently slower in some form. As such, any document would probably be an excellent bug report :-). As people run into performance issues with -CURRENT, the scheduler is one of the first variables I would ask someone to check, FYI. And in that sense, keeping 4BSD around is extremely valuable. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research