From patchwork Tue Aug 24 13:11:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergio Lopez X-Patchwork-Id: 12455001 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B693C432BE for ; Tue, 24 Aug 2021 13:14:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 11C2C60F8F for ; Tue, 24 Aug 2021 13:14:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 11C2C60F8F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:54258 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mIWGV-0006bo-1I for qemu-devel@archiver.kernel.org; Tue, 24 Aug 2021 09:14:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36884) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mIWF1-0005P6-Hf for qemu-devel@nongnu.org; Tue, 24 Aug 2021 09:13:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45581) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mIWEz-0006yX-4I for qemu-devel@nongnu.org; Tue, 24 Aug 2021 09:13:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629810799; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=S/sKbjiYvDUrqehLkwCDnHgdDPOoWGbm82SzDx5AAAQ=; b=HMiPN61/x42GL1DrWmYpLdxv/CYjvaVIr8QF+OXJLvx878uuxaL7kUjaqFIehcXe9Bo4gr PhJHe/iVIcVj20zYuAbtVZ/PbfW4sUWtZKDWO/zrktjVyqe5DTGQaQTK6AeIy0aa+/oaYz 1F8OHWkUmfwdiu+FSADYm6BechdSg6Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-60-vwEzWmPBNyC91gy5jr5zFQ-1; Tue, 24 Aug 2021 09:12:12 -0400 X-MC-Unique: vwEzWmPBNyC91gy5jr5zFQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 98904871803 for ; Tue, 24 Aug 2021 13:12:11 +0000 (UTC) Received: from toolbox.redhat.com (unknown [10.33.36.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8928C620DE; Tue, 24 Aug 2021 13:11:59 +0000 (UTC) From: Sergio Lopez To: qemu-devel@nongnu.org Subject: [PATCH] virtiofsd: Reverse req_list before processing it Date: Tue, 24 Aug 2021 15:11:58 +0200 Message-Id: <20210824131158.39970-1-slp@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=slp@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=slp@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.747, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, Sergio Lopez , "Dr. David Alan Gilbert" , Stefan Hajnoczi , vgoyal@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" With the thread pool disabled, we add the requests in the queue to a GList, processing by iterating over there afterwards. For adding them, we're using "g_list_prepend()", which is more efficient but causes the requests to be processed in reverse order, breaking the read-ahead and request-merging optimizations in the host for sequential operations. According to the documentation, if you need to process the request in-order, using "g_list_prepend()" and then reversing the list with "g_list_reverse()" is more efficient than using "g_list_append()", so let's do it that way. Testing on a spinning disk (to boost the increase of read-ahead and request-merging) shows a 4x improvement on sequential write fio test: Test: fio --directory=/mnt/virtio-fs --filename=fio-file1 --runtime=20 --iodepth=16 --size=4G --direct=1 --blocksize=4K --ioengine libaio --rw write --name seqwrite-libaio Without "g_list_reverse()": ... Jobs: 1 (f=1): [W(1)][100.0%][w=22.4MiB/s][w=5735 IOPS][eta 00m:00s] seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=710: Tue Aug 24 12:58:16 2021 write: IOPS=5709, BW=22.3MiB/s (23.4MB/s)(446MiB/20002msec); 0 zone resets ... With "g_list_reverse()": ... Jobs: 1 (f=1): [W(1)][100.0%][w=84.0MiB/s][w=21.5k IOPS][eta 00m:00s] seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=716: Tue Aug 24 13:00:15 2021 write: IOPS=21.3k, BW=83.1MiB/s (87.2MB/s)(1663MiB/20001msec); 0 zone resets ... Signed-off-by: Sergio Lopez Reviewed-by: Vivek Goyal --- tools/virtiofsd/fuse_virtio.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c index fc2564a603..8f4fd165b9 100644 --- a/tools/virtiofsd/fuse_virtio.c +++ b/tools/virtiofsd/fuse_virtio.c @@ -716,6 +716,7 @@ static void *fv_queue_thread(void *opaque) /* Process all the requests. */ if (!se->thread_pool_size && req_list != NULL) { + req_list = g_list_reverse(req_list); g_list_foreach(req_list, fv_queue_worker, qi); g_list_free(req_list); req_list = NULL;