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Re: [Qemu-devel] vga slow with -enable-kvm
From: |
Glauber Costa |
Subject: |
Re: [Qemu-devel] vga slow with -enable-kvm |
Date: |
Fri, 7 Nov 2008 08:17:52 -0200 |
On Fri, Nov 7, 2008 at 7:18 AM, Gerd Hoffmann <address@hidden> wrote:
> Hi,
>
> The vga display is very slow when using latest svn with kvm enabled.
> Just try to boot any linux kernel with vesafb enabled (vga=0x314 for
> address@hidden), enjoy watching the boot messages scroll. Booting without
> kvm enabled is *faster*.
>
> Feels like every single screen access is trapped or something like that.
> kvm_stat confirms that, there are tons of mmio exits:
The vga optimization is supposed to fix this. I noticed this too, and
maybe there's something
wrong per se. But since the result with the optimization was pretty
decent, I honestly didn't cared.
>
> address@hidden ~]# kvm_stat -1
> efer_reload 0 0
> exits 98234706 132054
> fpu_reload 6330433 0
> halt_exits 104372 0
> halt_wakeup 0 0
> host_state_reload 96499874 132038
> hypercalls 0 0
> insn_emulation 94632076 129954
> insn_emulation_fail 0 0
> invlpg 0 0
> io_exits 2627489 1653
> irq_exits 239675 397
> irq_window 11138 14
> largepages 0 0
> mmio_exits 93583132 129946
> mmu_cache_miss 38079 0
> mmu_flooded 37708 0
> mmu_pde_zapped 35810 0
> mmu_pte_updated 588299 0
> mmu_pte_write 647324 0
> mmu_recycled 0 0
> mmu_shadow_zapped 48191 0
> pf_fixed 1211070 1
> pf_guest 109462 0
> remote_tlb_flush 0 0
> request_irq 0 0
> signal_exits 164181 402
> tlb_flush 728218 44
>
> cheers,
> Gerd
>
>
>
--
Glauber Costa.
"Free as in Freedom"
http://glommer.net
"The less confident you are, the more serious you have to act."