From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikola Ciprich Subject: windows PIO question Date: Thu, 2 Feb 2012 22:16:30 +0100 Message-ID: <20120202211630.GA4719@nik-comp.lan> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="k+w/mQv8wyuph6w0" Cc: nikola.ciprich@linuxbox.cz To: kvm Return-path: Received: from gwu.lbox.cz ([62.245.111.132]:32878 "EHLO gwu.lbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756783Ab2BBV1H (ORCPT ); Thu, 2 Feb 2012 16:27:07 -0500 Received: from linuxbox.linuxbox.cz (linuxbox.linuxbox.cz [10.76.66.10]) by gwu.lbox.cz (Sendmail) with ESMTP id q12LGVMU028421 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 2 Feb 2012 22:16:31 +0100 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: --k+w/mQv8wyuph6w0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello everybody, I'm a bit confused regarding windows guests and PIO.. some time ago, I was = trying to find out, why one of my windows guests was running terribly slow. After checking the trace-cmd output, Avi stated that windows were using PIO= instead of DMA, after changing that, windows indeed got a lot faster. I didn't chec= k traces after that, but I'm now testing host with two windows 2003 guests, and che= cking the trac-cmd output, I see a lot of kvm_pio calls. While windows don't seem to be running particularly slow, they're not espec= ially fast either, and I'm wandering whether this could be related. But checking = IDE bus in guests, they seem to be using DMA which confuses me... so my questions is, what are the kvm_pio operations I see in traces, and ho= w can I tell what is OK and what is wrong, regarding disks DMA/PIO? If somebody could shed some light on this for me, I'd be very grateful... Thanks a lot in advance with best regards nikola ciprich --=20 ------------------------------------- Ing. Nikola CIPRICH LinuxBox.cz, s.r.o. 28. rijna 168, 709 01 Ostrava tel.: +420 596 603 142 fax: +420 596 621 273 mobil: +420 777 093 799 www.linuxbox.cz mobil servis: +420 737 238 656 email servis: servis@linuxbox.cz ------------------------------------- --k+w/mQv8wyuph6w0 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk8q/S4ACgkQ3xdJJrLygV62wACfeyYAuGqx7saXT0YZ426TUga5 iLgAoNtBt9P7OlIfBP+ZyxXtcSEjUrkh =Otts -----END PGP SIGNATURE----- --k+w/mQv8wyuph6w0--