From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47106) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtGbc-0005w5-K8 for qemu-devel@nongnu.org; Tue, 25 Nov 2014 08:56:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XtGbW-0002tW-5R for qemu-devel@nongnu.org; Tue, 25 Nov 2014 08:56:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49649) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtGbV-0002tQ-Ty for qemu-devel@nongnu.org; Tue, 25 Nov 2014 08:56:30 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sAPDuT9F029552 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 25 Nov 2014 08:56:29 -0500 Message-ID: <54748A88.9040605@redhat.com> Date: Tue, 25 Nov 2014 14:56:24 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1416902879-17422-1-git-send-email-famz@redhat.com> <20141125135243.GJ21126@stefanha-thinkpad.redhat.com> In-Reply-To: <20141125135243.GJ21126@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.3 0/5] aio: Support epoll by introducing qemu_poll abstraction List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Fam Zheng Cc: Kevin Wolf , qemu-devel@nongnu.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 25/11/2014 14:52, Stefan Hajnoczi wrote: > Do you think it is okay to forget about <1 ms timeout precision? > > If we go ahead with this, we'll need to rethink other timeouts in > QEMU. For example, is there a point in setting timer slack to 1 ns > if we cannot even specify ns wait times? > > Perhaps timerfd is needed before we can use epoll. Hopefully the > overall performance effect will be positive with epoll + timerfd, > compared to ppoll(). You can also use POLLIN with the epoll file descriptor, i.e. do ppoll followed (if there's no timeout) by epoll_wait with zero timeout. Paolo -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBAgAGBQJUdIqEAAoJEL/70l94x66DdtsH/RIXbk6faPWdb3MXaHmAoH1E z7q8cGuLPkI7XT54BYbiBFFn4MqS0XxLHLJ69CksFEC5u4wNl9vqsLLJrN/+uZe5 PznE7madjam32ZVtUbzfRwrBtO0KFgyXEiZfR9stAVXW+/KIUAaWU5rQ2IW6GqHg skt2GGmKfrCbyvmxVhSt2oMDRZ7O2Tquox6eLYizQX6JJ3/5vDqpzXTKE/Ix+wnt R3FA3IZkQuZMQPAFsMKj0AajN178RGiqXaB3UIR2YmPN1DWyjkfN05WmPgMpvZa/ eX70AhUdOjLzncfLU3bX9EAsml0s2Hsj5gKRYT6B5d8YK2b0ba3dCqgZRPV3+bo= =8Awx -----END PGP SIGNATURE-----