On Fri, 08 Apr 2011 19:50:57 -0500 Anthony Liguori <anthony@xxxxxxxxxxxxx> wrote: > On 04/08/2011 06:25 PM, Luiz Capitulino wrote: > > Hi there, > > > > Summary: > > > > - PXE boot in qemu.git (HEAD f124a41) is quite slow, more than 5 minutes. Got > > the problem with e1000, virtio and rtl8139. However, pcnet *works* (it's > > as fast as qemu-kvm.git) > > > > - PXE boot in qemu-kvm.git (HEAD df85c051) is fast, less than a minute. Tried > > with e1000, virtio and rtl8139 (I don't remember if I tried with pcnet) > > > > I tried with qemu.git v0.13.0 in order to check if this was a regression, but > > I got the same problem... > > > > Then I inspected qemu-kvm.git under the assumption that it could have a fix > > that wasn't commited to qemu.git. Found this: > > > > - commit 0836b77f0f65d56d08bdeffbac25cd6d78267dc9 which is merge, works > > > > - commit cc015e9a5dde2f03f123357fa060acbdfcd570a4 does not work (it's slow) > > > > I tried a bisect, but it brakes due to gcc4 vs. gcc3 changes. Then I inspected > > commits manually, and found out that commit 64d7e9a4 doesn't work, which makes > > me think that the fix could be in the conflict resolution of 0836b77f, which > > makes me remember that I'm late for diner, so my conclusions at this point are > > not reliable :) > > Can you run kvm_stat to see what the exit rates are? Here you go, both collected after the VM is fully booted: qemu.git: efer_reload 0 0 exits 159767195 99 fpu_reload 203 0 halt_exits 544 27 halt_wakeup 0 0 host_state_reload 299851 70 hypercalls 0 0 insn_emulation 134495973 41 insn_emulation_fail 0 0 invlpg 9687 0 io_exits 85979 0 irq_exits 162179 4 irq_injections 11582 27 irq_window 20712 27 largepages 0 0 mmio_exits 9545 41 mmu_cache_miss 5307 0 mmu_flooded 2493 0 mmu_pde_zapped 1188 0 mmu_pte_updated 5355 0 mmu_pte_write 181550 0 mmu_recycled 0 0 mmu_shadow_zapped 6437 0 mmu_unsync 15 0 nmi_injections 0 0 nmi_window 0 0 pf_fixed 73983 0 pf_guest 4027 0 remote_tlb_flush 1 0 request_irq 6 0 signal_exits 135731 2 tlb_flush 26760 0 qemu-kvm.git: efer_reload 0 0 exits 8697244 33 fpu_reload 46 0 halt_exits 206 8 halt_wakeup 7 0 host_state_reload 105173 8 hypercalls 0 0 insn_emulation 6984118 21 insn_emulation_fail 0 0 invlpg 9682 0 io_exits 626201 0 irq_exits 22930 4 irq_injections 2815 8 irq_window 1029 0 largepages 0 0 mmio_exits 3657 0 mmu_cache_miss 5271 0 mmu_flooded 2466 0 mmu_pde_zapped 1146 0 mmu_pte_updated 5294 0 mmu_pte_write 191173 0 mmu_recycled 0 0 mmu_shadow_zapped 6405 0 mmu_unsync 17 0 nmi_injections 0 0 nmi_window 0 0 pf_fixed 73580 0 pf_guest 4169 0 remote_tlb_flush 1 0 request_irq 0 0 signal_exits 24873 0 tlb_flush 26628 0 > > Maybe we're missing a coalesced io in qemu.git? It's also possible that > gpxe is hitting the apic or pit quite a lot. > > Regards, > > Anthony Liguori > > > Ideas? > > -- > > 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 > -- 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
