From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aurelien Jarno Subject: Re: Network performance regression between kvm-29 and kvm-31 Date: Sat, 21 Jul 2007 09:47:57 +0200 Message-ID: <46A1BA2D.30800@aurel32.net> References: <20070720222545.GB22656@hall.aurel32.net> <20070720225813.GA24368@hall.aurel32.net> <46A1A610.2050603@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Avi Kivity Return-path: In-Reply-To: <46A1A610.2050603-atKUWr5tajBWk0Htik3J/w@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 Avi Kivity a =E9crit : > Aurelien Jarno wrote: >> On Sat, Jul 21, 2007 at 12:25:45AM +0200, Aurelien Jarno wrote: >> = >>> Hi, >>> >>> I have just noticed that there is a huge performance regression in >>> network transfers between kvm-29 and kvm-31. Using the RTL8139 emulated >>> card, I have seen the network speed has been divided by 27!!! I haven't >>> made precise speed measurements with other emulated card, but the = >>> network speed has been reduced by the same order. >>> >>> Those tests have been done on a Core 2 CPU. >>> >>> After some tests I have seen that the problem lies in the user part. I >>> will do a git bisect tomorrow to find the patch that has caused the >>> problem, unless somebody already find it. >>> = >> 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 hel= d, 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. -- = .''`. Aurelien Jarno | GPG: 1024D/F1BCDB73 : :' : Debian developer | Electrical Engineer `. `' aurel32-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org | aurelien-rXXEIb44qovR7s880joybQ@public.gmane.org `- people.debian.org/~aurel32 | www.aurel32.net ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/