From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: kvm-27 vs 28 I/O speed Date: Mon, 16 Jul 2007 11:58:57 +0300 Message-ID: <469B3351.50508@qumranet.com> References: <1183748857.10287.198.camel@localhost> <1184180092.26210.49.camel@localhost> <4695BE06.6060609@qumranet.com> <1184263854.26210.89.camel@localhost> <46976EA7.2020202@qumranet.com> <68676e00707130627p32a43a63l3c6fe647242ec3e@mail.gmail.com> <46978110.5090303@qumranet.com> <1184351486.26210.101.camel@localhost> <68676e00707151227hb8b8538j706d9d0ee765ed41@mail.gmail.com> <68676e00707151407j1cf758e0ya7032c8c8577b982@mail.gmail.com> <68676e00707151422n2e1f0a07kc4ec10797edfa40c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: Luca Return-path: In-Reply-To: <68676e00707151422n2e1f0a07kc4ec10797edfa40c-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Luca wrote: > On 7/15/07, Luca wrote: >> On 7/15/07, Luca wrote: >> > On 7/13/07, Dave Hansen wrote: >> > > diff -ru kvm-fast-dmesg.txt kvm-slow-dmesg.txt >> > > >> > > Linux version 2.6.22 (dave@kernel) (gcc version 4.1.2 (Ubuntu >> 4.1.2-0ubuntu4)) #13 Wed Jul 11 15:27:01 PDT 2007 >> > >> > Is this a vanilla 2.6.22? 32 bit? >> > >> > > @@ -107,20 +90,21 @@ >> > > PIIX3: IDE controller at PCI slot 0000:00:01.1 >> > > PIIX3: chipset revision 0 >> > > PIIX3: not 100% native mode: will probe irqs later >> > > -PIIX3: neither IDE port enabled (BIOS) >> > > + ide0: BM-DMA at 0x1400-0x1407, BIOS settings: hda:pio, hdb:pio >> > > + ide1: BM-DMA at 0x1408-0x140f, BIOS settings: hdc:pio, hdd:pio >> > >> > Hum, FC6 PIIX driver always comes up with the same mode, regardless of >> > what I'm doing to the controller... >> >> Ok, now I'm confused... >> >> pci_config_write: PIIX3 IDE: addr=40 val=00008000 len=2 >> pci_config_write: PIIX3 IDE: addr=42 val=00008000 len=2 >> >> I'm using KVM-27 userspace, and the BIOS is enabling both ports. So... >> linux shouldn't think that the ports are disabled (yet I saw the same >> thing with FC7 and libata). > > Oh fuck, it's obvious... If you don't supply -L on the command line > KVM ends up using the BIOS in the default system directory > (/usr/share{,local}/qemu); on my system this the BIOS installed by > QEMU 0.9, which does *not* enable the IDE ports. OTOH the BIOS file > shipped with KVM does enable the ports. > I guess that you're seeing the same thing: you used to run KVM+QEMU > bios (ports disabled - fast); then KVM started to enable IDE ports > (even with QEMU bios) and you saw a regression. > Can you re-test KVM 27 with it's BIOS (i.e. use something like -L > ~/src/kvm-27/qemu/pc-bios)? > > FYI I'm seeing a better tput with MWDMA2 (ports enabled) rather than > with PIO (ports disabled). So, would it be correct to revert the patch enabling the ports, assuming people use the kvm-supplied bios? -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/