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 22:18:19 +0200 Message-ID: <4DA3620B.5020101@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> <1302552848.3589.89.camel@x201> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig0C8477B6FC26FA9AC2ECBC1E" Cc: Luiz Capitulino , Anthony Liguori , qemu-devel@nongnu.org, kvm@vger.kernel.org, avi@redhat.com, mtosatti@redhat.com, mst@redhat.com, blauwirbel@gmail.com To: Alex Williamson Return-path: Received: from fmmailgate03.web.de ([217.72.192.234]:44733 "EHLO fmmailgate03.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755476Ab1DKUST (ORCPT ); Mon, 11 Apr 2011 16:18:19 -0400 In-Reply-To: <1302552848.3589.89.camel@x201> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig0C8477B6FC26FA9AC2ECBC1E Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2011-04-11 22:14, Alex Williamson wrote: > On Mon, 2011-04-11 at 22:04 +0200, Jan Kiszka wrote: >> 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? >> >>> >>> So, does this have to be fixed w/o I/O thread? >> >> If it's most probably an architectural deficit of non-io-thread mode, = I >> would say let it rest in peace. But maybe it points to a generic issue= s >> that is just magnified by non-threaded mode. >=20 > I've probably been told, but forget. Why isn't io-thread enabled by > default? Thanks, TCG performance still sucks in io-threaded mode. I've three patches in my queue that reduces the overhead a bit further - for me to a reasonable level (will post them the next days). But, still, YMMV depending on the workload. At least Windows should no longer we a functional blocker thanks to Paolo's work. Jan --------------enig0C8477B6FC26FA9AC2ECBC1E 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/ iEYEARECAAYFAk2jYgsACgkQitSsb3rl5xQ8mACg4N6uSI3ixJwBcI/7PNipKdc9 pzgAn23q9uiD0/1WN1G0D9AmLY6qJfd+ =1aGj -----END PGP SIGNATURE----- --------------enig0C8477B6FC26FA9AC2ECBC1E--