Re: [PATCH v3 0/4] mm/folio_zero_user: add multi-page clearing

[Raghavendra K T <raghavendra.kt@amd.com>]

On 4/23/2025 12:52 AM, Ankur Arora wrote:
> 
> Raghavendra K T <raghavendra.kt@amd.com> writes:
[...]
>>
>> SUT: AMD EPYC 9B24 (Genoa) preempt=lazy
>>
>> metric = time taken in sec (lower is better). total SIZE=64GB
>>                   mm/folio_zero_user    x86/folio_zero_user     change
>>    pg-sz=1GB       2.47044  +-  0.38%    1.060877  +-  0.07%    57.06
>>    pg-sz=2MB       5.098403 +-  0.01%    2.52015   +-  0.36%    50.57
> 
> 
> Just to translate it into the same units I was using above:
> 
>                    mm/folio_zero_user        x86/folio_zero_user
>     pg-sz=1GB       25.91 GBps +-  0.38%    60.37 GBps +-  0.07%
>     pg-sz=2MB       12.57 GBps +-  0.01%    25.39 GBps +-  0.36%
> 
> That's a decent improvement over Milan. Btw, are you using boost=1?
> 

yes boost=1

> Also, any idea why the huge delta in the mm/folio_zero_user 2MB, 1GB
> cases? Both of these are doing 4k page at a time, so the huge delta
> is a little head scratching.
> 
> There's a gap on Milan as well but it is much smaller.
> 

Need to think/analyze further, but from perf stat I see
glaring difference in:
			2M		1G
pagefaults		32,906		202
iTLB-load-misses	44,490		156

- Raghu