[PATCH] [AArch64] Refines the Cortex-A57 Machine Model

[James Molloy]

Hi Dave,

I’ve discovered that we should be running the FPLoadBalancing pass AFTER
the Post-RA scheduler. We aren’t, and I thought we were.

The FPLoadBalancing pass is sensitive to instruction order - a permutation
such as might be expected if the post-RA scheduler does its job could
cause worse performance.

I’ve looked into switching it to later but it exposed a couple of bugs, so
I’m working on fixing those first.

Cheers,
James

On 18/09/2014 17:34, "Dave Estes" <cestes at codeaurora.org> wrote:

>Jianging,
>
>I did some more runs and I've got mixed news. Seems I've been a bit more
>focused on this new model's gains over -mcpu=generic rather than using
>the existing A57 model as a baseline. The reason was primarily because
>our earlier testing showed the existing A57 model performing very
>poorly. However, I re-did my runs using the existing A57 model as a
>baseline and it actually performs really well. So that's the good news.
>The mediocre news is that increasing the accuracy of the model has
>merely shifted performance around and not actually increased it.
>
>With that said, I'm going to do some more experimenting and then I'm
>going to try to model the in-order and out-of-order resources
>accordingly in a hope that I can capture the best gains. It might take a
>bit of time, but I'll hopefully replace this patch with those efforts.
>
>In the meantime, I might have some questions for you guys but I'll take
>that chatter off-list.
>
>-Dave
>
>--
>Employee of Qualcomm Innovation Center, Inc.
>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
>
>


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