From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: I/O performance of VirtIO Date: Mon, 26 Oct 2009 10:35:49 +0200 Message-ID: <4AE55F65.7050906@redhat.com> References: <20091012204901.GA10688@nightfall.luchs.at> <4AD3A38D.3090102@msgid.tls.msk.ru> <4AD41FB8.6000209@web.de> <4AE0885A.1080304@redhat.com> <7A331778-3227-43B1-B2E2-A6BE6F92C834@suse.de> <4AE3E5B0.5080700@redhat.com> <4AE559FC.4060400@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Alexander Graf , Michael Tokarev , =?UTF-8?B?UmVuw6kgUGZlaWZmZXI=?= , "kvm@vger.kernel.org" To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:36797 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754999AbZJZIgP (ORCPT ); Mon, 26 Oct 2009 04:36:15 -0400 In-Reply-To: <4AE559FC.4060400@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On 10/26/2009 10:12 AM, Jan Kiszka wrote: >> No. Dedicated I/O threads provide parallelism. All latency needs is to >> have SIGIO sent on all file descriptors (or rather, in qemu-kvm with >> irqchip, to have all file descriptors in the poll() call). >> >> Jan, does slirp add new connections to the select set? >> >> > It should do so in slirp_select_fill (it iterates over all TCP&UDP > sockets of all instances). I think without doing this, slirp wouldn't > receive a single bit at all (no activity without FD_ISSET). > Yes, so it seems from the code. But something is missing if you get better performance with -no-kvm-irqchip. Perhaps timers are off. -- error compiling committee.c: too many arguments to function