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Re: [Qemu-devel] Re: branches are expensive
From: |
Laurent Desnogues |
Subject: |
Re: [Qemu-devel] Re: branches are expensive |
Date: |
Thu, 19 Mar 2009 12:06:47 +0100 |
On Thu, Mar 19, 2009 at 11:39 AM, Steffen Liebergeld <address@hidden> wrote:
> Laurent Desnogues <address@hidden> schrieb:
>> On Thu, Mar 19, 2009 at 11:07 AM, Steffen Liebergeld <address@hidden> wrote:
>>>
>>> I've tested Qemu 0.10.0 and with i386-softmmu on a i386 host I get the
>>> following numbers:
>>> direct jump count 70%, 2 jumps 54%
>>>
>>> For qemu-system-arm on an ARM host, the numbers look like this:
>>> direct jump count 47%, 2 jumps 40%
>>>
>>> For completeness I tested qemu-system-arm on a i386 host as well:
>>> direct jump count 44%, 2 jumps 37%
>>>
>>> So it looks like the chaining on ARM targets is not as effective as on i386
>>> targets (regardless of the guest, I used the same guest setup, compiled for
>>> different architectures, on all tests). Do you have any ideas why this is
>>> the
>>> case?
>>
>> Different instruction sets, different compilers. You'd better compare
>> guest code before drawing any conclusion.
>
> The qemu-system-arm on ARM and i386 were compiled by the same compiler.
I said "guest" not "host" :)
You need to compare ARM and i386 blocks *before* translation.
Laurent
- [Qemu-devel] branches are expensive, Steffen Liebergeld, 2009/03/17
- Re: [Qemu-devel] branches are expensive, Avi Kivity, 2009/03/17
- [Qemu-devel] Re: branches are expensive, Jan Kiszka, 2009/03/17
- [Qemu-devel] Re: branches are expensive, Steffen Liebergeld, 2009/03/17
- Re: [Qemu-devel] Re: branches are expensive, Paul Brook, 2009/03/17
- Re: [Qemu-devel] Re: branches are expensive, Avi Kivity, 2009/03/17
- [Qemu-devel] Re: branches are expensive, Steffen Liebergeld, 2009/03/19
- Re: [Qemu-devel] Re: branches are expensive, Laurent Desnogues, 2009/03/19
- [Qemu-devel] Re: branches are expensive, Steffen Liebergeld, 2009/03/19
- Re: [Qemu-devel] Re: branches are expensive,
Laurent Desnogues <=
- Re: [Qemu-devel] Re: branches are expensive, Avi Kivity, 2009/03/19
- Re: [Qemu-devel] Re: branches are expensive, Paul Brook, 2009/03/19
[Qemu-devel] Re: branches are expensive, Steffen Liebergeld, 2009/03/17
Re: [Qemu-devel] branches are expensive, Laurent Desnogues, 2009/03/17