Re: [PATCH v2] dma-buf: system_heap: use larger contiguous mappings instead of per-page mmap

[Sumit Semwal]

Hi Barry,

On Fri, 21 Nov 2025 at 06:54, Barry Song <21cn...@gmail.com> wrote:
>
> Hi Sumit,
>
> >
> > Using the micro-benchmark below, we see that mmap becomes
> > 3.5X faster:
>
>
> Marcin pointed out to me off-tree that it is actually 35x faster,
> not 3.5x faster. Sorry for my poor math. I assume you can fix this
> when merging it?

Sure, I corrected this, and is merged to drm-misc-next

Thanks,
Sumit.
>
> >
> > W/ patch:
> >
> > ~ # ./a.out
> > mmap 512MB took 200266.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 198151.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 197069.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 196781.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 198102.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 195552.000 us, verify OK
> >
> > W/o patch:
> >
> > ~ # ./a.out
> > mmap 512MB took 6987470.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 6970739.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 6984383.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 6971311.000 us, verify OK
> > ~ # ./a.out
> > mmap 512MB took 6991680.000 us, verify OK
>
>
> Thanks
> Barry