Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261713AbVBXB3g (ORCPT ); Wed, 23 Feb 2005 20:29:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261763AbVBXB3g (ORCPT ); Wed, 23 Feb 2005 20:29:36 -0500 Received: from smtp200.mail.sc5.yahoo.com ([216.136.130.125]:4766 "HELO smtp200.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261713AbVBXB3Y (ORCPT ); Wed, 23 Feb 2005 20:29:24 -0500 Message-ID: <421D2DEE.8070209@yahoo.com.au> Date: Thu, 24 Feb 2005 12:29:18 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20050105 Debian/1.7.5-1 X-Accept-Language: en MIME-Version: 1.0 To: Lee Revell CC: Hugh Dickins , Ingo Molnar , Andrew Morton , linux-kernel Subject: Re: More latency regressions with 2.6.11-rc4-RT-V0.7.39-02 References: <1109182061.16201.6.camel@krustophenia.net> <1109187381.3174.5.camel@krustophenia.net> <1109190614.3126.1.camel@krustophenia.net> <421D1171.7070506@yahoo.com.au> <1109207024.4516.6.camel@krustophenia.net> In-Reply-To: <1109207024.4516.6.camel@krustophenia.net> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1213 Lines: 31 Lee Revell wrote: > On Thu, 2005-02-24 at 10:27 +1100, Nick Piggin wrote: >>If you are using i386 with 2-level page tables (no highmem), then >>the behaviour should be more or less identical. Odd. > > > IIRC last time I really tested this a few months ago, the worst case > latency on that machine was about 150us. Currently its 422us from the > same clear_page_range code path. > > On my Athlon XP the clear_page_range latency is not showing up at all, > and the worst delay so far is only 35us, most of which is the timer > interrupt IOW that machine is showing the best achievable latency (with > PREEMPT_DESKTOP). The machine seeing 422 us latencies in > clear_page_range is a 600Mhz C3, which is known to be a FSB limited > architecture. > Well it should be pretty trivial to add a break in there. I don't think it can get into 2.6.11 at this point though, so we'll revisit this for 2.6.12 if the clear_page_range optimisations don't get anywhere. Nick - 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/