From patchwork Wed Jun 17 13:21:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 280243 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=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MIME_BASE64_TEXT,SIGNED_OFF_BY,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 B835EC433E0 for ; Wed, 17 Jun 2020 13:23:24 +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 87A582098B for ; Wed, 17 Jun 2020 13:23:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CmRmjnyy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87A582098B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42404 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jlY2F-000458-M7 for qemu-devel@archiver.kernel.org; Wed, 17 Jun 2020 09:23:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47480) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jlY1F-0002DM-23 for qemu-devel@nongnu.org; Wed, 17 Jun 2020 09:22:21 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:53248 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jlY1D-0002le-Kd for qemu-devel@nongnu.org; Wed, 17 Jun 2020 09:22:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592400138; 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: in-reply-to:in-reply-to:references:references; bh=GgNnXjQJLjsUTRKKTVtMZ/B9j1jc9+hdmKfY2K8Dqjo=; b=CmRmjnyyG6HBRD/iouQSybULLgLO2636bn/sEZzVTMUbJOZl73fxmbTVxRn93snxwUAovh KELzAreuxJVx7ISCR4wNgUJwDYIGJUM6V0l8IwiEBM10E8i//BHo2i1TY+9cCEP8aAUzw6 F+ssb0D/WHLUuYVFKYVqTGS8nVso4Sg= 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-210-0NHw3vrpMaCLFJ7GnzYXQA-1; Wed, 17 Jun 2020 09:22:14 -0400 X-MC-Unique: 0NHw3vrpMaCLFJ7GnzYXQA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4F248835B7B; Wed, 17 Jun 2020 13:22:13 +0000 (UTC) Received: from localhost (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 058057E59F; Wed, 17 Jun 2020 13:22:09 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v2 1/7] block/nvme: poll queues without q->lock Date: Wed, 17 Jun 2020 14:21:55 +0100 Message-Id: <20200617132201.1832152-2-stefanha@redhat.com> In-Reply-To: <20200617132201.1832152-1-stefanha@redhat.com> References: <20200617132201.1832152-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.61; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/17 02:02:46 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MIME_BASE64_TEXT=1.741, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: Kevin Wolf , Fam Zheng , qemu-block@nongnu.org, Max Reitz , Stefan Hajnoczi , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" A lot of CPU time is spent simply locking/unlocking q->lock during polling. Check for completion outside the lock to make q->lock disappear from the profile. Signed-off-by: Stefan Hajnoczi --- block/nvme.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/block/nvme.c b/block/nvme.c index eb2f54dd9d..e4375ec245 100644 --- a/block/nvme.c +++ b/block/nvme.c @@ -512,6 +512,18 @@ static bool nvme_poll_queues(BDRVNVMeState *s) for (i = 0; i < s->nr_queues; i++) { NVMeQueuePair *q = s->queues[i]; + const size_t cqe_offset = q->cq.head * NVME_CQ_ENTRY_BYTES; + NvmeCqe *cqe = (NvmeCqe *)&q->cq.queue[cqe_offset]; + + /* + * Do an early check for completions. q->lock isn't needed because + * nvme_process_completion() only runs in the event loop thread and + * cannot race with itself. + */ + if ((le16_to_cpu(cqe->status) & 0x1) == q->cq_phase) { + continue; + } + qemu_mutex_lock(&q->lock); while (nvme_process_completion(s, q)) { /* Keep polling */