From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Network performance regression between kvm-29 and kvm-31 Date: Sun, 22 Jul 2007 13:30:14 +0300 Message-ID: <46A331B6.7020306@qumranet.com> References: <20070720222545.GB22656@hall.aurel32.net> <20070720225813.GA24368@hall.aurel32.net> <46A1A610.2050603@qumranet.com> <46A1BA2D.30800@aurel32.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Aurelien Jarno Return-path: In-Reply-To: <46A1BA2D.30800-rXXEIb44qovR7s880joybQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Aurelien Jarno wrote: >>> >>> I finally didn't resist to run git bisect before going to bed... >>> >>> The patch that causes the regression is: >>> >>> commit 7d2e674835492040c9baddf0989a95abea9a8d0f >>> Author: Avi Kivity >>> Date: Sun Jul 15 15:08:23 2007 +0300 >>> >>> kvm: qemu: synchronous signal handling >>> >>> in order to ensure that signals are handled with the global lock held, we >>> block them, and dequeue them with sigtimedwait(). we can then call the >>> handlers directly. >>> >>> this ensures that the device model and internal qemu data structures are not >>> corrupted by cpu 0 thread handling a signal while cpu 1 is servicing a pio >>> or mmio request. >>> >>> >>> >> Is this with -net user or -net tap? >> >> > > With -net tap. > > I pushed a commit which fixes a latency issue with that commit. However with my test (ping -f against the host) I only get a x2 performance increase. Can you test kvm-userspace.git? And can you detail your benchmark? -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/