From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id DF972C5B552 for ; Tue, 10 Jun 2025 12:40:56 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uOyET-00016d-SJ; Tue, 10 Jun 2025 08:37:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uOyEM-000123-RQ for qemu-devel@nongnu.org; Tue, 10 Jun 2025 08:37:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uOyEK-0000LB-BC for qemu-devel@nongnu.org; Tue, 10 Jun 2025 08:37:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749559046; 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=HPC5fL9ZgHxTmRf/UnDDKNb3x7TqATZwHvx2CTeh1eI=; b=eUKD/YpvzgzxjnbotW2xUjPqGv20XNMHhhkkMHzI/X5OC+cgqIt0zEc7E6kVeiO4PHrZ6E UMKhlJDzn2QbnblrwNdm8pW8N+auqau1wK7+QoGG3yusA1byGkLyNVRb3R5H0YV0SoTF8t xIiw4xaAAA9IGx2HvllNIznPpVQR2C8= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-15-mTewK1llPf68HWOll7F2Yg-1; Tue, 10 Jun 2025 08:37:23 -0400 X-MC-Unique: mTewK1llPf68HWOll7F2Yg-1 X-Mimecast-MFC-AGG-ID: mTewK1llPf68HWOll7F2Yg_1749559041 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3ECF4195604F; Tue, 10 Jun 2025 12:37:21 +0000 (UTC) Received: from toolbx.redhat.com (unknown [10.42.28.87]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id EB19530001B1; Tue, 10 Jun 2025 12:37:18 +0000 (UTC) From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , "Michael S. Tsirkin" , Peter Maydell , qemu-block@nongnu.org, Stefan Hajnoczi , Kevin Wolf , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH 03/31] block: skip automatic zero-init of large array in ioq_submit Date: Tue, 10 Jun 2025 13:36:41 +0100 Message-ID: <20250610123709.835102-4-berrange@redhat.com> In-Reply-To: <20250610123709.835102-1-berrange@redhat.com> References: <20250610123709.835102-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The 'ioq_submit' method has a struct array that is 8k in size. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'iocbs' array will selectively initialized when processing the I/O data. Signed-off-by: Daniel P. Berrangé --- block/linux-aio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/linux-aio.c b/block/linux-aio.c index 407369f5c9..c200e7ad20 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -291,7 +291,7 @@ static void ioq_submit(LinuxAioState *s) { int ret, len; struct qemu_laiocb *aiocb; - struct iocb *iocbs[MAX_EVENTS]; + QEMU_UNINITIALIZED struct iocb *iocbs[MAX_EVENTS]; QSIMPLEQ_HEAD(, qemu_laiocb) completed; do { -- 2.49.0