|
| From: | Peter Lieven |
| Subject: | Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists |
| Date: | Tue, 21 Feb 2012 11:50:47 +0100 |
| User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110921 Thunderbird/3.1.15 |
On 20.02.2012 21:45, Gleb Natapov wrote:
On Mon, Feb 20, 2012 at 08:59:38PM +0100, Peter Lieven wrote:On 20.02.2012 20:04, Gleb Natapov wrote:On Mon, Feb 20, 2012 at 08:40:08PM +0200, Gleb Natapov wrote:On Mon, Feb 20, 2012 at 07:17:55PM +0100, Peter Lieven wrote:Hi, I came a across an issue with a Windows 7 (32-bit) as well as with a Windows 2008 R2 (64-bit) guest. If I transfer a file from the VM via CIFS or FTP to a remote machine, i get very poor read performance (around 13MB/s). The VM peaks at 100% cpu and I see a lot of insn_emulations and all kinds of exists in kvm_stat efer_reload 0 0 exits 2260976 79620 fpu_reload 6197 11 halt_exits 114734 5011 halt_wakeup 111195 4876 host_state_reload 1499659 60962 hypercalls 0 0 insn_emulation 1577325 58488 insn_emulation_fail 0 0 invlpg 0 0 io_exits 943949 40249Hmm, too many of those.irq_exits 108679 5434 irq_injections 236545 10788 irq_window 7606 246 largepages 672 5 mmio_exits 460020 16082 mmu_cache_miss 119 0 mmu_flooded 0 0 mmu_pde_zapped 0 0 mmu_pte_updated 0 0 mmu_pte_write 13474 9 mmu_recycled 0 0 mmu_shadow_zapped 141 0 mmu_unsync 0 0 nmi_injections 0 0 nmi_window 0 0 pf_fixed 22803 35 pf_guest 0 0 remote_tlb_flush 239 2 request_irq 0 0 signal_exits 0 0 tlb_flush 20933 0 If I run the same VM with a Ubuntu 10.04.4 guest I get around 60MB/s throughput. The kvm_stats look a lot more sane. efer_reload 0 0 exits 6132004 17931 fpu_reload 19863 3 halt_exits 264961 3083 halt_wakeup 236468 2959 host_state_reload 1104468 3104 hypercalls 0 0 insn_emulation 1417443 7518 insn_emulation_fail 0 0 invlpg 0 0 io_exits 869380 2795 irq_exits 253501 2362 irq_injections 616967 6804 irq_window 201186 2161 largepages 1019 0 mmio_exits 205268 0 mmu_cache_miss 192 0 mmu_flooded 0 0 mmu_pde_zapped 0 0 mmu_pte_updated 0 0 mmu_pte_write 7440546 0 mmu_recycled 0 0 mmu_shadow_zapped 259 0 mmu_unsync 0 0 nmi_injections 0 0 nmi_window 0 0 pf_fixed 38529 30 pf_guest 0 0 remote_tlb_flush 761 1 request_irq 0 0 signal_exits 0 0 tlb_flush 0 0 I use virtio-net (with vhost-net) and virtio-blk. I tried disabling hpet (which basically illiminated the mmio_exits, but does not increase performance) and also commit (39a7a362e16bb27e98738d63f24d1ab5811e26a8 ) - no improvement. My commandline: /usr/bin/qemu-kvm-1.0 -netdev type=tap,id=guest8,script=no,downscript=no,ifname=tap0,vhost=on -device virtio-net-pci,netdev=guest8,mac=52:54:00:ff:00:d3 -drive format=host_device,file=/dev/mapper/iqn.2001-05.com.equallogic:0-8a0906-eeef4e007-a8a9f3818674f2fc-lieven-windows7-vc-r80788,if=virtio,cache=none,aio=native -m 2048 -smp 2 -monitor tcp:0:4001,server,nowait -vnc :1 -name lieven-win7-vc -boot order=dc,menu=off -k de -pidfile /var/run/qemu/vm-187.pid -mem-path /hugepages -mem-prealloc -cpu host -rtc base=localtime -vga std -usb -usbdevice tablet -no-hpet What further information is needed to debug this further?Which kernel version (looks like something recent)? Which host CPU (looks like something old)?Output of cat /proc/cpuinfoWhich Windows' virtio drivers are you using? Take a trace like described here http://www.linux-kvm.org/page/Tracing (with -no-hpet please).And also "info pci" output from qemu monitor while we are at it.here is the output while i was tracing. you can download the trace i took while i did a ftp transfer from the vm: -> http://82.141.21.156/report.txt.gzWindows reads PM timer. A lot. 15152 times per second. Can you try to run this command in Windows guest: bcdedit /set {default} useplatformclock false I hope it will make Windows use TSC instead, but you can't be sure about anything with Windows :(
Whatever it does now it eates more CPU has almost equal
number of exits and throughput is about the same (15MB/s).
If pmtimer is at 0xb008 it still reads it like hell.
I checked with bcedit /v that useplatformclock is set to "No".
I still wonder why both virtio devices are on IRQ0 ?
New Trace:
http://82.141.21.156/report2.txt.gz
efer_reload 0 0
exits 1510993 59343
fpu_reload 6729 10
halt_exits 93603 5913
halt_wakeup 95698 5849
host_state_reload 738523 24727
hypercalls 0 0
insn_emulation 678416 20107
insn_emulation_fail 0 0
invlpg 0 0
io_exits 703291 28436
irq_exits 102117 7527
irq_injections 217335 14344
irq_window 9926 650
largepages 573 8
mmio_exits 27 0
mmu_cache_miss 148 0
mmu_flooded 0 0
mmu_pde_zapped 0 0
mmu_pte_updated 0 0
mmu_pte_write 0 0
mmu_recycled 0 0
mmu_shadow_zapped 190 0
mmu_unsync 0 0
nmi_injections 0 0
nmi_window 0 0
pf_fixed 21938 38
pf_guest 0 0
remote_tlb_flush 20 0
request_irq 0 0
signal_exits 0 0
tlb_flush 11711 0
QEMU 1.0 monitor - type 'help' for more information
(qemu) info pci
info pci
Bus 0, device 0, function 0:
Host bridge: PCI device 8086:1237
id ""
Bus 0, device 1, function 0:
ISA bridge: PCI device 8086:7000
id ""
Bus 0, device 1, function 1:
IDE controller: PCI device 8086:7010
BAR4: I/O at 0xc080 [0xc08f].
id ""
Bus 0, device 1, function 2:
USB controller: PCI device 8086:7020
IRQ 5.
BAR4: I/O at 0xc040 [0xc05f].
id ""
Bus 0, device 1, function 3:
Bridge: PCI device 8086:7113
IRQ 9.
id ""
Bus 0, device 2, function 0:
VGA controller: PCI device 1234:1111
BAR0: 32 bit prefetchable memory at 0xfd000000 [0xfdffffff].
BAR6: 32 bit memory at 0xffffffffffffffff [0x0000fffe].
id ""
Bus 0, device 3, function 0:
Ethernet controller: PCI device 1af4:1000
IRQ 0.
BAR0: I/O at 0xc060 [0xc07f].
BAR1: 32 bit memory at 0xfebf0000 [0xfebf0fff].
BAR6: 32 bit memory at 0xffffffffffffffff [0x0000fffe].
id ""
Bus 0, device 4, function 0:
SCSI controller: PCI device 1af4:1001
IRQ 0.
BAR0: I/O at 0xc000 [0xc03f].
BAR1: 32 bit memory at 0xfebf1000 [0xfebf1fff].
id ""
| [Prev in Thread] | Current Thread | [Next in Thread] |