On 7/13/07, Anthony Liguori <[EMAIL PROTECTED]> wrote: > Dave Hansen wrote: > > On Fri, 2007-07-13 at 16:41 +0300, Avi Kivity wrote: > > > >> I tested FC6 i386 about found no difference with or without the patch. > >> > > > > I've git bisected down the the same patch that you pasted above. I've > > also tried just applying that single patch to kvm-27 and reproduced the > > slow behavior. > > > > > >> Dave, can you diff the guest dmesg with kvm-27 and kvm-28 userspace? > >> Maybe that will tell us something. > >> > > > > Here's kvm-27 and kvm-27+55a3212bc2...: > > > > > > diff -ru kvm-fast-dmesg.txt kvm-slow-dmesg.txt > > > > Linux version 2.6.22 ([EMAIL PROTECTED]) (gcc version 4.1.2 (Ubuntu > > 4.1.2-0ubuntu4)) #13 Wed Jul 11 15:27:01 PDT 2007 > > BIOS-provided physical RAM map: > > @@ -39,7 +22,7 @@ > > Enabling unmasked SIMD FPU exception support... done. > > Initializing CPU#0 > > PID hash table entries: 512 (order: 9, 2048 bytes) > > -Detected 2669.668 MHz processor. > > +Detected 2669.011 MHz processor. > > Console: colour VGA+ 80x25 > > Dentry cache hash table entries: 16384 (order: 4, 65536 bytes) > > Inode-cache hash table entries: 8192 (order: 3, 32768 bytes) > > @@ -53,7 +36,7 @@ > > .data : 0xc036efcf - 0xc043911c ( 808 kB) > > .text : 0xc0100000 - 0xc036efcf (2491 kB) > > Checking if this processor honours the WP bit even in supervisor mode... > > Ok. > > -Calibrating delay using timer specific routine.. 26758.82 BogoMIPS > > (lpj=53517640) > > +Calibrating delay using timer specific routine.. 26800.00 BogoMIPS > > (lpj=53600004) > > Mount-cache hash table entries: 512 > > CPU: L1 I cache: 8K > > CPU: L2 cache: 128K > > @@ -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 > > > > There's your problem. With that patch, your kernel is using PIO instead > of DMA. > > I'm not 100% sure what's going here other than the fact that this > particular problem has cropped up a number of times on qemu-devel. It's > been very difficult to get all guests to actually use DMA.
Those are the BIOS settings, which are consistent with what QEMU is doing. Linux driver is actually configuring the device for MWDMA2 Luca ------------------------------------------------------------------------- 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/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
