From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC PATCH 00/17] virtual-bus Date: Fri, 03 Apr 2009 15:25:24 +0300 Message-ID: <49D60034.1010508@redhat.com> References: <49D49C1F.6030306@novell.com> <200904022243.21088.rusty@rustcorp.com.au> <49D4B4A3.5070008@novell.com> <49D4B87D.2000202@redhat.com> <20090402145018.GA816@gondor.apana.org.au> <49D4D301.2090209@redhat.com> <20090402154041.GA1774@gondor.apana.org.au> <49D4E072.2060003@redhat.com> <20090402160941.GB2173@gondor.apana.org.au> <49D4EDBD.3050900@redhat.com> <20090402170610.GA3001@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Gregory Haskins , Rusty Russell , anthony@codemonkey.ws, andi@firstfloor.org, linux-kernel@vger.kernel.org, agraf@suse.de, pmullaney@novell.com, pmorreale@novell.com, netdev@vger.kernel.org, kvm@vger.kernel.org, Ingo Molnar To: Herbert Xu Return-path: Received: from mx2.redhat.com ([66.187.237.31]:55323 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755430AbZDCMZM (ORCPT ); Fri, 3 Apr 2009 08:25:12 -0400 In-Reply-To: <20090402170610.GA3001@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: Herbert Xu wrote: > On Thu, Apr 02, 2009 at 07:54:21PM +0300, Avi Kivity wrote: > >> 3ms latency for ping? >> >> (ping will always be scheduled immediately when the reply arrives if I >> understand cfs, so guest load won't delay it) >> > > That only happens if the guest immediately does some CPU-intensive > computation 3ms and assuming its timeslice lasts that long. > Note that this happens even if the computation is SCHED_BATCH. > In any case, the same thing will happen right now if the host or > some other guest on the same CPU hogs the CPU for 3ms. > > If the host is overloaded, that's fair. But millisecond latencies without host contention is not a good result. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.