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
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
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