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 A2A13CCD184 for ; Thu, 9 Oct 2025 14:20:37 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v6rUp-0003mn-93; Thu, 09 Oct 2025 10:19:56 -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 1v6rUk-0003l4-VI for qemu-devel@nongnu.org; Thu, 09 Oct 2025 10:19:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v6rUZ-0001Dk-QU for qemu-devel@nongnu.org; Thu, 09 Oct 2025 10:19:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760019573; 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: in-reply-to:in-reply-to:references:references; bh=r2YadN+V0dVcUq19cJvvb4fSZ983CWhwZUO1+F8mmec=; b=ThxpGZqTfGK6OLWIhhG93esb3OyeabOSq8YAGBRFjsXBsIwPC/KwPqo2U/cE1SvnrEZpvu z8ggRafyjVRYBV8HHVGAM9v2Q/M17NoKoxDbQiAg28vL/5LKTKN+D2n21NyAtAOuc+2RGo +mRpGqmwiRCLVm6wrujupZ3N5UAnGeU= Received: from mx-prod-mc-03.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-672-KAIfbnXVMNeDpVRbxbjh5A-1; Thu, 09 Oct 2025 10:19:30 -0400 X-MC-Unique: KAIfbnXVMNeDpVRbxbjh5A-1 X-Mimecast-MFC-AGG-ID: KAIfbnXVMNeDpVRbxbjh5A_1760019567 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E0F6619560B2; Thu, 9 Oct 2025 14:19:26 +0000 (UTC) Received: from redhat.com (unknown [10.44.32.99]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 30AAF18004D8; Thu, 9 Oct 2025 14:19:22 +0000 (UTC) Date: Thu, 9 Oct 2025 16:19:20 +0200 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Aarushi Mehta , Fam Zheng , Stefano Garzarella , Hanna Czenczek , eblake@redhat.com, qemu-block@nongnu.org, hibriansong@gmail.com, Stefan Weil , Paolo Bonzini , Chao Gao Subject: Re: [PATCH v4 02/12] aio-posix: keep polling enabled with fdmon-io_uring.c Message-ID: References: <20250910175703.374499-1-stefanha@redhat.com> <20250910175703.374499-3-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250910175703.374499-3-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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 Am 10.09.2025 um 19:56 hat Stefan Hajnoczi geschrieben: > Commit 816a430c517e ("util/aio: Defer disabling poll mode as long as > possible") kept polling enabled when the event loop timeout is 0. Since > there is no timeout the event loop will continue immediately and the > overhead of disabling and re-enabling polling can be avoided. > > fdmon-io_uring.c is unable to take advantage of this optimization > because its ->need_wait() function returns true whenever there are new > io_uring SQEs to submit: > > if (timeout || ctx->fdmon_ops->need_wait(ctx)) { > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > Polling will be disabled even when timeout == 0. > > Extend the optimization to handle the case when need_wait() returns true > and timeout == 0. > > Cc: Chao Gao > Signed-off-by: Stefan Hajnoczi > Reviewed-by: Eric Blake Reviewed-by: Kevin Wolf