Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754028AbZJCI51 (ORCPT ); Sat, 3 Oct 2009 04:57:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751420AbZJCI50 (ORCPT ); Sat, 3 Oct 2009 04:57:26 -0400 Received: from mail-bw0-f210.google.com ([209.85.218.210]:36177 "EHLO mail-bw0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbZJCI5Z (ORCPT ); Sat, 3 Oct 2009 04:57:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:subject:date:user-agent:cc:mime-version:content-disposition :content-type:content-transfer-encoding:message-id; b=Sk7wxhp6l7etOWlU7tiMy+euG2RWGV97IoIxmmW9s8cIDjWHQI1zRFrL92z8pVrBsf AIHA8S8lZj4uvhxFcB6CSPIH0GjjeXydZ7Xf/puhyxxrMB0hOTxhmtqCs2m1WBhv8UWr ++I22nm0uqV4chhRNDOi8sHoAiCZBW5NLNPoM= From: Corrado Zoccolo To: "Linux-Kernel" , Jens Axboe , Jeff Moyer Subject: [PATCH] cfq: enable idle for seeky processes on rotational NCQ devices Date: Sat, 3 Oct 2009 10:57:41 +0200 User-Agent: KMail/1.11.4 (Linux/2.6.31cz; KDE/4.2.4; i686; ; ) Cc: Vivek Goyal , Mike Galbraith MIME-Version: 1.0 Content-Disposition: inline Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <200910031057.41695.czoccolo@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1663 Lines: 40 Idle window is currently disabled for seeky processes on all NCQ devices. This is causing large latencies when seeky processes are competing with async writes, for rotational NCQ devices. This patch, based on Vivek Goyal's original idea (http://lkml.org/lkml/2009/7/12/110), enables idle window for seeky processes on rotational NCQ devices. As for non-NCQ devices, a smaller idle window (2ms) is used for seeky processes compared to normal I/O (8ms). RAIDs should be marked as non-rotational as well (and probably a better flag name should be devised), since they can carry multiple operations in parallel. Signed-off-by: Corrado Zoccolo --- diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 1ca813b..7116f11 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1951,10 +1951,12 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || - (cfqd->hw_tag && CIC_SEEKY(cic))) + (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag && CIC_SEEKY(cic))) enable_idle = 0; else if (sample_valid(cic->ttime_samples)) { - if (cic->ttime_mean > cfqd->cfq_slice_idle) + unsigned idle_time = CIC_SEEKY(cic) ? CFQ_MIN_TT + : cfqd->cfq_slice_idle; + if (cic->ttime_mean > idle_time) enable_idle = 0; else enable_idle = 1; -- 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/