Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262113AbUKVNkh (ORCPT ); Mon, 22 Nov 2004 08:40:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262102AbUKVNiY (ORCPT ); Mon, 22 Nov 2004 08:38:24 -0500 Received: from apollo.nbase.co.il ([194.90.137.2]:61961 "EHLO apollo.nbase.co.il") by vger.kernel.org with ESMTP id S262100AbUKVNfu (ORCPT ); Mon, 22 Nov 2004 08:35:50 -0500 Message-ID: <41A1EAE0.9080504@mrv.com> Date: Mon, 22 Nov 2004 15:34:24 +0200 From: emann@mrv.com (Eran Mann) User-Agent: Mozilla Thunderbird 0.9 (X11/20041103) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.30-2 References: <20041111144414.GA8881@elte.hu> <20041111215122.GA5885@elte.hu> <20041116125402.GA9258@elte.hu> <20041116130946.GA11053@elte.hu> <20041116134027.GA13360@elte.hu> <20041117124234.GA25956@elte.hu> <20041118123521.GA29091@elte.hu> <20041118164612.GA17040@elte.hu> <20041122005411.GA19363@elte.hu> <41A1A6E6.5090807@mrv.com> <20041122100140.GD6817@elte.hu> In-Reply-To: <20041122100140.GD6817@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 988 Lines: 29 Ingo Molnar wrote: > * Eran Mann wrote: >> >>Hi, >>I?m seeing latencies of up to ~2000 microseconds. see attached traces >>file for a small sample. I think I?m missing something obvious >>config-wise but I don?t know what... ... > this seems to imply IDE DMA related hardware overhead. Apparently what > happens is that with certain motherboards/chipsets, if IDE DMA happens > then that DMA transfer _completely locks up_ the system bus. Nothing > happens, and the CPU is stalled in essence until the end of the DMA > request. > .... > Ingo Right on. After hdparm -d0 I see maximum latency of 35 us after a full kernel build with a few GUI apps in the background. I?ll try to find a reasonable compromise. -- Eran Mann - 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/