From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=59262 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q8MOD-0008GK-Kg for qemu-devel@nongnu.org; Fri, 08 Apr 2011 20:51:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q8MOC-0006Io-Fb for qemu-devel@nongnu.org; Fri, 08 Apr 2011 20:51:01 -0400 Received: from mail-gx0-f173.google.com ([209.85.161.173]:61583) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q8MOC-0006Ij-Ab for qemu-devel@nongnu.org; Fri, 08 Apr 2011 20:51:00 -0400 Received: by gxk26 with SMTP id 26so2000503gxk.4 for ; Fri, 08 Apr 2011 17:50:59 -0700 (PDT) Message-ID: <4D9FAD71.5020503@codemonkey.ws> Date: Fri, 08 Apr 2011 19:50:57 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <20110408202525.26c45c05@doriath> In-Reply-To: <20110408202525.26c45c05@doriath> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: Slow PXE boot in qemu.git (fast in qemu-kvm.git) List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com, qemu-devel@nongnu.org, blauwirbel@gmail.com, alex.williamson@redhat.com, avi@redhat.com On 04/08/2011 06:25 PM, Luiz Capitulino wrote: > Hi there, > > Summary: > > - PXE boot in qemu.git (HEAD f124a41) is quite slow, more than 5 minutes. Got > the problem with e1000, virtio and rtl8139. However, pcnet *works* (it's > as fast as qemu-kvm.git) > > - PXE boot in qemu-kvm.git (HEAD df85c051) is fast, less than a minute. Tried > with e1000, virtio and rtl8139 (I don't remember if I tried with pcnet) > > I tried with qemu.git v0.13.0 in order to check if this was a regression, but > I got the same problem... > > Then I inspected qemu-kvm.git under the assumption that it could have a fix > that wasn't commited to qemu.git. Found this: > > - commit 0836b77f0f65d56d08bdeffbac25cd6d78267dc9 which is merge, works > > - commit cc015e9a5dde2f03f123357fa060acbdfcd570a4 does not work (it's slow) > > I tried a bisect, but it brakes due to gcc4 vs. gcc3 changes. Then I inspected > commits manually, and found out that commit 64d7e9a4 doesn't work, which makes > me think that the fix could be in the conflict resolution of 0836b77f, which > makes me remember that I'm late for diner, so my conclusions at this point are > not reliable :) Can you run kvm_stat to see what the exit rates are? Maybe we're missing a coalesced io in qemu.git? It's also possible that gpxe is hitting the apic or pit quite a lot. Regards, Anthony Liguori > Ideas? > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html