On Mon, Dec 14, 2020 at 7:07 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> Subject: mm: speedup mremap on 1GB or larger regions
>
> Android needs to move large memory regions for garbage collection. The GC
> requires moving physical pages of multi-gigabyte heap using mremap.
> During this move, the application threads have to be paused for
> correctness. It is critical to keep this pause as short as possible to
> avoid jitters during user interaction.
It would have been good to add a pointer to the PMD case we did earlier..
Also, a few comments on the actual performance in practice would be
nice. Does this actually *trigger* on Android in practice?
I can well imagine the PMD case triggering easily, but are there
real-life Android loads that really do gigabyte heaps? That sounds a
bit odd to me.
So I don't have any complaints about the patch, but I just wonder how
_realistic_ this actually is, particularly the alleged 13x improvement
in timing...
Linus
