From: Michael Tokarev <mjt@tls.msk.ru>
To: KVM list <kvm@vger.kernel.org>
Subject: *insane* amount of host_state_reloads for openbsd guest in 0.14
Date: Fri, 11 Mar 2011 15:02:33 +0300 [thread overview]
Message-ID: <4D7A0F59.1060604@msgid.tls.msk.ru> (raw)
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
mmio_exits 20057 226
irq_injections 6533 223
pf_fixed 9801 176
mmu_pte_write 17781 111
irq_exits 6490 20
fpu_reload 133 1
halt_exits 422 0
mmu_cache_miss 333 0
halt_wakeup 30 0
mmu_shadow_zapped 358 0
remote_tlb_flush 3 0
signal_exits 1 0
After booting, idle guest sitting at login: prompt:
host_state_reload 28675531 44171
exits 25184108 3379
insn_emulation 22784490 3266
irq_injections 54139 200
mmio_exits 52748 122
mmu_pte_write 41584 100
halt_exits 22731 99
irq_exits 9220 12
io_exits 6912620 9
fpu_reload 765 1
pf_fixed 12419 0
mmu_shadow_zapped 358 0
mmu_cache_miss 339 0
halt_wakeup 38 0
remote_tlb_flush 3 0
signal_exits 1 0
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:
kvm 0.12 and idle guest:
exits 25975600 3329
insn_emulation 23555272 3229
host_state_reload 1898575 3117
irq_injections 13125 200
mmio_exits 26603 122
mmu_pte_write 61515 100
halt_exits 5173 100
irq_exits 6927 1
fpu_reload 499 1
io_exits 7058999 1
pf_fixed 11902 0
mmu_shadow_zapped 634 0
mmu_cache_miss 558 0
halt_wakeup 166 0
remote_tlb_flush 2 0
signal_exits 1 0
Again, running on the same AthlonII machine with 2.6.37 host
kernel, freshly installed openbsd 4.3 32bit guest (with all
defaults).
FreeBSD does not show this behavour.
What it can be?
Thanks!
/mjt
next reply other threads:[~2011-03-11 12:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-11 12:02 Michael Tokarev [this message]
2011-03-14 10:00 ` *insane* amount of host_state_reloads for openbsd guest in 0.14 Daniel Bareiro
2011-03-16 19:48 ` Marcelo Tosatti
2011-03-16 19:55 ` Michael Tokarev
2011-03-17 7:24 ` Gleb Natapov
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