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Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exist
From: |
Gleb Natapov |
Subject: |
Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists |
Date: |
Mon, 20 Feb 2012 20:40:08 +0200 |
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 40249
Hmm, 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)?
Which Windows' virtio drivers are you using?
Take a trace like described here http://www.linux-kvm.org/page/Tracing
(with -no-hpet please).
Try to use -cpu host,+x2apic. It may help Linux guest performance.
--
Gleb.
- [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/20
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists,
Gleb Natapov <=
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Gleb Natapov, 2012/02/20
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/20
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/20
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Gleb Natapov, 2012/02/20
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/21
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Gleb Natapov, 2012/02/21
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/21
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Gleb Natapov, 2012/02/21
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Peter Lieven, 2012/02/21
- Re: [Qemu-devel] win7 bad i/o performance, high insn_emulation and exists, Gleb Natapov, 2012/02/21