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 22:29:42 +0200 Message-ID: <4DA364B6.2000300@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> <4DA3620B.5020101@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEC6D5DBADFB8E34F218EB5BD" 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 fmmailgate01.web.de ([217.72.192.221]:48446 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751534Ab1DKU3m (ORCPT ); Mon, 11 Apr 2011 16:29:42 -0400 In-Reply-To: <4DA3620B.5020101@web.de> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEC6D5DBADFB8E34F218EB5BD Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2011-04-11 22:18, Jan Kiszka wrote: > 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 *= 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 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-k= vm. >>>>> Can you re-configure and build with that and see if it's fast? Tha= nks, >>>> >>>> Yes, nice catch, it's faster with I/O thread enabled, even seem fast= er >>>> 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 issu= es >>> that is just magnified by non-threaded mode. >> >> I've probably been told, but forget. Why isn't io-thread enabled by >> default? Thanks, >=20 > 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. In fact, they were already prepared. So I've just sent them out. Jan --------------enigEC6D5DBADFB8E34F218EB5BD 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/ iEYEARECAAYFAk2jZLYACgkQitSsb3rl5xTH2gCgqVLSMy7RG14AfapdLxIsqYEf ZOQAoO3SqvW+Jq5uAnZGFKJj7x2K21DK =jkyV -----END PGP SIGNATURE----- --------------enigEC6D5DBADFB8E34F218EB5BD--