Re: [linux-next:master] [mm] 7b32f64bc5: pts.svt-av1.Preset13.Bosphorus4K.frames_per_second 45.8% regression

On Mon, Jul 27, 2026 at 10:17:21AM +0800, Oliver Sang wrote:
> quite sorry that we lost the machine we reported this regression, and since
> pts running need some specific settings in our test framework, we still need
> some time to setup on other test machines, we cannot start the test soon. will
> keep you updated.

Hi Oliver,

No worries at all, take your time.

I should mention that my patch may not fully fix the regression reported
here. It is just based on my analysis of the code path, but I haven't been
able to reproduce the exact SVT-AV1 workload.

To better understand the issue, would you please share some information
about the memory access pattern of the pts.svt-av1 test case? For example:

  - Does SVT-AV1 mmap the input video file, or use read()?
  - If mmap'd, are there multiple VMAs over the same file
    (e.g., from mprotect or partial mappings)?
  - What is the typical VMA size relative to the file size?
  - Is the access pattern sequential, random, or a mix?

This would help us understand whether the regression comes from the
async readahead blocking I described in my reply to Frederick, or from
a different interaction with _max_index.

Thanks,
Bo