From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Slow PXE boot in qemu.git (fast in qemu-kvm.git) Date: Mon, 11 Apr 2011 23:18:06 +0200 Message-ID: <4DA3700E.6010006@web.de> References: <20110408202525.26c45c05@doriath> <4D9FAD71.5020503@codemonkey.ws> <20110411153519.37f8316a@doriath> <1302548432.3589.78.camel@x201> <20110411161555.49688970@doriath> <4DA35EE4.6090303@web.de> <20110411180523.219530d7@doriath> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig42F44DC4216D9A5FBFB8A63F" Cc: Alex Williamson , Anthony Liguori , qemu-devel@nongnu.org, kvm@vger.kernel.org, avi@redhat.com, mtosatti@redhat.com, mst@redhat.com, blauwirbel@gmail.com To: Luiz Capitulino Return-path: Received: from fmmailgate01.web.de ([217.72.192.221]:35895 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986Ab1DKVSJ (ORCPT ); Mon, 11 Apr 2011 17:18:09 -0400 In-Reply-To: <20110411180523.219530d7@doriath> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig42F44DC4216D9A5FBFB8A63F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2011-04-11 23:05, Luiz Capitulino wrote: > On Mon, 11 Apr 2011 22:04:52 +0200 > Jan Kiszka wrote: >=20 >> On 2011-04-11 21:15, Luiz Capitulino wrote: >>> On Mon, 11 Apr 2011 13:00:32 -0600 >>> Alex Williamson wrote: >>> >>>> On Mon, 2011-04-11 at 15:35 -0300, Luiz Capitulino wrote: >>>>> On Fri, 08 Apr 2011 19:50:57 -0500 >>>>> Anthony Liguori wrote: >>>>> >>>>>> 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 *w= orks* (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 w= ith pcnet) >>>>>>> >>>> >>>> I was having this problem too, but I think it's because I forgot to >>>> build qemu with --enable-io-thread, which is the default for qemu-kv= m. >>>> Can you re-configure and build with that and see if it's fast? Than= ks, >>> >>> Yes, nice catch, it's faster with I/O thread enabled, even seem faste= r >>> than qemu-kvm.git. >> >> What's the performance under qemu-kvm with -no-kvm-irqchip? >=20 > Still fast,=20 I meant: is it even faster with unaccelerated userspace irqchip? I've seen such effects with emulated NICs before. > but just realized that qemu-kvm's configure says that I/O thread > is disabled: >=20 > IO thread no >=20 > And it's fast.. That only means (so far) that the upstream io-thread code is disabled. Qemu-kvm's own solution is enabled all the time, and you can't switch to upstream anyway as both are incompatible. That's going to change soon (hopefully) when we migrate qemu-kvm to the upstream version. Jan --------------enig42F44DC4216D9A5FBFB8A63F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/ iEYEARECAAYFAk2jcA4ACgkQitSsb3rl5xTbiwCgnW5dRwPLOUfgvOaPO4DBl3cE rRUAn0QtKC0YAYcIxkst8bFIQoxuu+5g =7KUk -----END PGP SIGNATURE----- --------------enig42F44DC4216D9A5FBFB8A63F--