Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262577AbVE0UcR (ORCPT ); Fri, 27 May 2005 16:32:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262578AbVE0UcR (ORCPT ); Fri, 27 May 2005 16:32:17 -0400 Received: from smtp.lnxw.com ([207.21.185.24]:18698 "EHLO smtp.lnxw.com") by vger.kernel.org with ESMTP id S262577AbVE0UcN (ORCPT ); Fri, 27 May 2005 16:32:13 -0400 Date: Fri, 27 May 2005 13:36:55 -0700 To: Ingo Molnar Cc: Bill Huey , Nick Piggin , Andi Kleen , Sven-Thorsten Dietrich , dwalker@mvista.com, hch@infradead.org, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: RT patch acceptance Message-ID: <20050527203655.GB1940@nietzsche.lynx.com> References: <20050524192029.2ef75b89.akpm@osdl.org> <20050525063306.GC5164@elte.hu> <1117044019.5840.32.camel@sdietrich-xp.vilm.net> <20050526193230.GY86087@muc.de> <1117138270.1583.44.camel@sdietrich-xp.vilm.net> <20050526202747.GB86087@muc.de> <4296ADE9.50805@yahoo.com.au> <20050527120812.GA375@nietzsche.lynx.com> <20050527121056.GA2238@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050527121056.GA2238@elte.hu> User-Agent: Mutt/1.5.9i From: Bill Huey (hui) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1201 Lines: 27 On Fri, May 27, 2005 at 02:10:56PM +0200, Ingo Molnar wrote: > * Bill Huey wrote: > > > There's really no good reason why this kernel can't get the same > > latency as a nanokernel. The scheduler paths are riddled with SMP > > rebalancing stuff and the like which contributes to overall system > > latency. Remove those things and replace it with things like direct > > CPU pining and you'll start seeing those numbers collapse. [...] > > could you be a bit more specific? None of that stuff should show up on > UP kernels. Even on SMP, rebalancing is either asynchronous, or O(1). I found out a couple of problems with IRQ rebalancing in that the latency spread was effected by a ping-ponging of the actual interrupt itself. I reported this to you in November and I fixed this problem by gluing the interrupt to the same cpu as the irq-thread. Not sure if it was the rebalancing or the cache issues, but they seem related. bill - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/