From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41147) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R8Yk6-0005qA-R9 for qemu-devel@nongnu.org; Tue, 27 Sep 2011 10:34:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R8Yk5-0003en-Qp for qemu-devel@nongnu.org; Tue, 27 Sep 2011 10:34:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51333) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R8Yk5-0003ed-Hl for qemu-devel@nongnu.org; Tue, 27 Sep 2011 10:34:41 -0400 Message-ID: <4E81DEEA.10208@redhat.com> Date: Tue, 27 Sep 2011 17:34:18 +0300 From: Avi Kivity MIME-Version: 1.0 References: <4E78C42D.5030207@siemens.com> <20110921080600.GA9847@stefanha-thinkpad.localdomain> <4E80B50B.9000301@siemens.com> <4E80B55F.5020203@redhat.com> <4E80BFF3.8000907@us.ibm.com> <4E8190BE.3000801@redhat.com> <4E81D609.1060203@siemens.com> <4E81D88B.4020504@codemonkey.ws> <4E81DDDF.8050201@siemens.com> In-Reply-To: <4E81DDDF.8050201@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] Use qemu_eventfd for POSIX AIO List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Kevin Wolf , Anthony Liguori , Stefan Hajnoczi , Marcelo Tosatti , qemu-devel On 09/27/2011 05:29 PM, Jan Kiszka wrote: > > > > Moreover, the eventfd() counter is not lossy (practically speaking) whereas if > > you use pipe() as a counter, it will be lossy in practice. > > > > This is why posix aio uses pipe() and not eventfd(). > > I don't get this yet. eventfd is lossy by default. It only decreases the > counter on read if you specify EFD_SEMAPHORE - which we do not do. > It's not lossy - a read returns the number of events written since the last read. -- error compiling committee.c: too many arguments to function