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. Regards, Anthony Liguori > hda: QEMU HARDDISK, ATA DISK drive > hdb: QEMU HARDDISK, ATA DISK drive > -Clocksource tsc unstable (delta = 767711774 ns) > +ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 > +Clocksource tsc unstable (delta = 768021683 ns) > Time: pit clocksource has been installed. > hdc: QEMU CD-ROM, ATAPI CD/DVD-ROM drive > -ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 > ide1 at 0x170-0x177,0x376 on irq 15 > hda: max request size: 512KiB > -hda: 10485760 sectors (5368 MB) w/256KiB Cache, CHS=10402/255/63 > +hda: 10485760 sectors (5368 MB) w/256KiB Cache, CHS=10402/255/63, (U)DMA > hda: cache flushes supported > hda: hda1 > hdb: max request size: 512KiB > -hdb: 262144 sectors (134 MB) w/256KiB Cache, CHS=260/255/63 > +hdb: 262144 sectors (134 MB) w/256KiB Cache, CHS=260/255/63, (U)DMA > hdb: cache flushes supported > hdb: hdb1 > serio: i8042 KBD port at 0x60,0x64 irq 1 > @@ -146,7 +130,7 @@ > Adding 128480k swap on /dev/hdb1. Priority:-1 extents:1 across:128480k > Checking root file system... > fsck 1.37 (21-Mar-2005) > -/dev/hda1: clean, 46970/655360 files, 287821/1309289 blocks > +/dev/hda1: clean, 46970/655360 files, 287829/1309289 blocks > EXT3 FS on hda1, internal journal > Cleaning up ifupdown...done. > Checking all file systems... > > Looks like the slow versions have DMA enabled. Is it slower to emulate > DMA than PIO? > > -- Dave > > > ------------------------------------------------------------------------- > 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 > > ------------------------------------------------------------------------- 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
