On Mon, Feb 20, 2012 at 08:15:15PM +0100, Peter Lieven wrote: > On 20.02.2012 19:40, 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 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)? > 2.6.38 with kvm-kmod 3.2 > >Which host CPU (looks like something old)? > why? i guess its (quite) new. > Yes, it is. I misread the kvm_stat data and thought that CPU does not have ept, but it does. > vendor_id : GenuineIntel > cpu family : 6 > model : 44 > model name : Intel(R) Xeon(R) CPU L5640 @ 2.27GHz > stepping : 2 > cpu MHz : 1596.000 > cache size : 12288 KB > physical id : 1 > siblings : 6 > core id : 10 > cpu cores : 6 > apicid : 52 > initial apicid : 52 > fpu : yes > fpu_exception : yes > cpuid level : 11 > wp : yes > flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge > mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe > syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts > rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 > monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 > sse4_2 popcnt aes lahf_lm arat dts tpr_shadow vnmi flexpriority ept > vpid > bogomips : 2254.43 > clflush size : 64 > cache_alignment : 64 > address sizes : 40 bits physical, 48 bits virtual > > >Which Windows' virtio drivers are you using? > i used to use 0.1-16 and today also tried 0.1-22 from > http://alt.fedoraproject.org/pub/alt/virtio-win/latest/images/ > >Take a trace like described here http://www.linux-kvm.org/page/Tracing > >(with -no-hpet please). > will prepare this. > >Try to use -cpu host,+x2apic. It may help Linux guest performance. > Thanks, it improved throughput a little while lowering the > cpu usage. Windows does not support this? > Not yet. It will support something similar when qemu will have hyper-v support. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
