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[Qemu-devel] Re: [PATCH] CONFIG_MMU_MAP powerpc host support
From: |
Piotras |
Subject: |
[Qemu-devel] Re: [PATCH] CONFIG_MMU_MAP powerpc host support |
Date: |
Mon, 20 Dec 2004 22:31:34 +0100 |
Great!
Do you have an estimate of possible performance gain by introducing
direct pointer to mmu_map for memory read?
I have two ideas for future experimentation.
There is a trick possible without wasting another register for global
variable: use two copies of CPUState (one for privileged and another
for user mode), then make mmu_map.add_read first member of the
struct. This would introduce guest register coping for user/supervisor
switch, but maybe performance gain would justify this.
Another idea: if we could align add_read/add_write on 64k boundary,
"addi" could be removed.
Regards,
Piotrek
On Mon, 20 Dec 2004 18:55:21 +0100, Magnus Damm <address@hidden> wrote:
> Hello,
>
> This patch adds powerpc host support to the CONFIG_MMU_MAP patch
> written by Piotrek. My patch should be applied on top of
> v1-part[1-3].patch.gz. I have only tested the code with a x86 guest on
> a ppc host running Linux - someone, please test on a host running OSX.
>
> Performance gain reported by nbench:
>
> Memory index: 50%
> Integer index: 44%
> Fp index: 4%
>
> Right now each map-memory access consists of 5-6 powerpc instructions.
> If a direct pointer to mem_map could be kept in a register then we
> would be down to 3-4 instructions per memoy access...
>
> / magnus
- [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Magnus Damm, 2004/12/20
- [Qemu-devel] Re: [PATCH] CONFIG_MMU_MAP powerpc host support,
Piotras <=
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Laurent Amon, 2004/12/24
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Norikatsu Shigemura, 2004/12/25
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Laurent Amon, 2004/12/27
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Pierre d'Herbemont, 2004/12/27
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Laurent Amon, 2004/12/27
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Daniel Egger, 2004/12/28
- Re: [Qemu-devel] [PATCH] CONFIG_MMU_MAP powerpc host support, Pierre d'Herbemont, 2004/12/28