Jay Foad via llvm-dev
2021-Mar-09 14:03 UTC
[llvm-dev] llvm-mca for in-order CPUs (was Re: LLVM Weekly - #375, March 8th 2021)
On Mon, 8 Mar 2021 at 18:33, LLVM Weekly <list at llvmweekly.org> wrote:> * The llvm-mca static performance analysis tool now support in-order CPUs such > as the Arm Cortex-A55. [d791695](https://reviews.llvm.org/rGd791695cb517).Thanks for doing this! I am very interested in using it for the AMDGPU target. Have you given any thought to targets with MicroOpBufferSize=1? I understand that these are also "in order". I found that I could get some tests running with these changes: https://reviews.llvm.org/differential/diff/329308/ But I am really shooting in the dark here. I don't have a good understanding of the difference between MicroOpBufferSize=0 and 1, and I am not even sure which setting is really best for AMDGPU. Thanks, Jay.
Andrew Savonichev via llvm-dev
2021-Mar-09 16:33 UTC
[llvm-dev] llvm-mca for in-order CPUs (was Re: LLVM Weekly - #375, March 8th 2021)
Hi Jay, Jay Foad writes:> On Mon, 8 Mar 2021 at 18:33, LLVM Weekly <list at llvmweekly.org> wrote: >> * The llvm-mca static performance analysis tool now support in-order CPUs such >> as the Arm Cortex-A55. [d791695](https://reviews.llvm.org/rGd791695cb517). > > Thanks for doing this! I am very interested in using it for the AMDGPU > target.So far the feature was only tested for ARM in-order CPUs, so it will be great if you can try it for the AMDGPU target!> Have you given any thought to targets with MicroOpBufferSize=1? > I understand that these are also "in order". I found that I could get > some tests running with these changes: > https://reviews.llvm.org/differential/diff/329308/ > > But I am really shooting in the dark here. I don't have a good > understanding of the difference between MicroOpBufferSize=0 and 1, and > I am not even sure which setting is really best for AMDGPU.Frankly, I don't know what is the difference between MicroOpBufferSize=0 and 1. We should probably treat them the same for MCA, so your changes look good. -- Andrew