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Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] ARM CPU Speed simulated by Qemu? |
Date: |
Tue, 12 Sep 2006 15:34:27 +0100 |
User-agent: |
KMail/1.9.4 |
> How much do misses on the branch prediction level cost? How much
> pipeline interlocks? I don't think those would be _that_ dramatic. Since
> today's compilers are said to be optimizing quite well...
It all depends on the code you're running. Certainly branch prediction can
have a major effect if the hardware consistently gets it wrong. Even arm
hardware has 5/7 stage pipelines that need flushing on a mispredict.
Pipeline interlocks are likely to be relatively small, for most Arm hardware
at least (ia64 is a completely different story :-). As a compiler author I'd
generally expect a few % performance improvement from a good scheduling
model.
I wouldn't assuming the compiler gets everything right, as it's quite common
for systems to be built for the lowest common denominator target.
Paul
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- Re: [Qemu-devel] Re: qemu-system-sparc video problem on 16 bitdisplays, Juergen Lock, 2006/09/08
- Re: [Qemu-devel] Re: qemu-system-sparc video problem on 16 bitdisplays, Blue Swirl, 2006/09/08
- Re: [Qemu-devel] Re: qemu-system-sparc video problem on 16 bitdisplays, Stuart Brady, 2006/09/11
- [Qemu-devel] ARM CPU Speed simulated by Qemu?, Tieu Ma Dau, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?, nyos, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?, Paul Brook, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?, Markus Schiltknecht, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?, Paul Brook, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?, Markus Schiltknecht, 2006/09/12
- Re: [Qemu-devel] ARM CPU Speed simulated by Qemu?,
Paul Brook <=