From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:38970) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hBMPY-0006Jk-03 for qemu-devel@nongnu.org; Tue, 02 Apr 2019 12:37:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hBMDu-0001VM-TV for qemu-devel@nongnu.org; Tue, 02 Apr 2019 12:25:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46746) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hBMDu-0001SG-G2 for qemu-devel@nongnu.org; Tue, 02 Apr 2019 12:25:18 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BA5F43082134 for ; Tue, 2 Apr 2019 16:25:17 +0000 (UTC) References: <20190326131822.GD15011@stefanha-x1.localdomain> <55751c00-0854-ea4d-75b5-ab82b4eeb70d@redhat.com> <20190402161853.GE5352@localhost.localdomain> From: Paolo Bonzini Message-ID: Date: Tue, 2 Apr 2019 18:25:04 +0200 MIME-Version: 1.0 In-Reply-To: <20190402161853.GE5352@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] QEMU event loop optimizations List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Stefan Hajnoczi , Sergio Lopez , qemu-devel@nongnu.org On 02/04/19 18:18, Kevin Wolf wrote: > Am 26.03.2019 um 15:11 hat Paolo Bonzini geschrieben: >> - but actually (and a precursor to using IOCB_CMD_POLL) it should be >> possible to have just one LinuxAioState per AioContext, and then >> it can simply share the AioContext's EventNotifier. This removes >> the need to do the event_notifier_test_and_clear in linux-aio.c. > > Isn't having only one LinuxAioState per AioContext what we already do? > See aio_get_linux_aio(). And I should have known that: commit 0187f5c9cb172771ba85c66e3bf61f8cde6d6561 Author: Paolo Bonzini Date: Mon Jul 4 18:33:20 2016 +0200 linux-aio: share one LinuxAioState within an AioContext This has better performance because it executes fewer system calls and does not use a bottom half per disk. Originally proposed by Ming Lei. The second point, which is to share the AioContext's EventNotifier, still stands. Paolo