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

hi, Bo,

On Mon, Jul 27, 2026 at 12:20:22PM +0800, Bo Zhang wrote:
> 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:

unfortunately, we just simply integrate "Phoronix Test Suite" [1] into our
test framework, and for now we still keep on 9.4.1 version [2] since we don't
have enough bandwidth to do upgrade recently. and for svt-av1, we now use
2.11.1 version [3]. we don't have enough knowledge to dig deep for your
questions. sorry about this.

[1] http://www.phoronix-test-suite.com/
[2] http://phoronix-test-suite.com/releases/phoronix-test-suite-9.4.1.tar.gz
[3] https://github.com/phoronix-test-suite/phoronix-test-suite/tree/master/ob-cache/test-profiles/pts/svt-av1-2.11.1
> 
>   - 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