16.03.2011 22:48, Marcelo Tosatti wrote: > On Fri, Mar 11, 2011 at 03:02:33PM +0300, Michael Tokarev wrote: >> I tried Openbsd 4.8 in kvm today and immediately noticed >> that it is running _very_ slow, boot takes several minutes >> to complete to the "login:" prompt. After investigating >> I found that kvm does really insane amount of host_state_reloads. >> Here are typical kvm_stats: >> >> During bootup while checking/mounting filesystems etc: >> >> host_state_reload 13782074 671689 >> exits 24071297 45751 >> insn_emulation 21707073 45353 >> io_exits 6900215 288 [] >> After booting, idle guest sitting at login: prompt: >> >> host_state_reload 28675531 44171 >> exits 25184108 3379 >> insn_emulation 22784490 3266 >> irq_injections 54139 200 [] >> So I played with various options for a bit and found that: >> >> o 0.14 -no-kvm-irqchip gets rid of host_state_reloads, making >> them to be the same (+/-100) as insn_emulations, and speeds >> up guest significantly (and lowers CPU usage on host during >> guest idle time). >> >> o 0.14 -no-kvm makes the guest *faster* than w/o any additional >> options, reducing boot time for about 50% (but increasing host >> CPU usage to maximum) >> >> o 0.12 without any options is the fastest, and it keeps number >> of reloads to be within 3k/sec range during all time. here's >> typical kvm_stats of idle guest with 0.12: >> > Perhaps OpenBSD is accessing the HPET frequently, which is emulated > in userspace. Try disabling it with "-no-hpet". -no-hpet makes no visible difference, exactly the same thing as above: host_state_reload 21310655 43968 exits 25007599 3573 insn_emulation 22635201 3469 Thanks! /mjt -- 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
