Re: [LSF/MM/BPF TOPIC]mTHP reliable allocation and reclamation

[Barry Song <21cnbao@gmail.com>]

On Thu, May 16, 2024 at 3:19 PM Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>
>
>
> On 2024/5/16 08:25, Barry Song wrote:
> > On Thu, May 16, 2024 at 11:41 AM Matthew Wilcox <willy@infradead.org> wrote:
> >>
> >> On Fri, May 10, 2024 at 02:22:02PM +1200, Barry Song wrote:
> >>> - The allocation of mTHP isn't consistently reliable; even after
> >>> prolonged use, obtaining large folios
> >>>    remains uncertain.
> >>>    As an instance, following a few hours of operation, the likelihood
> >>> of successfully allocating large
> >>>    folios on a phone may decrease to just 2%.
> >>
> >> I'd be curious to know whether you're using a filesystem that supports
> >> large folios or whether the pagecache is full of small folios?  The more
> >> places that allocate large folios, the easier it becomes to allocate
> >> large folios.
> >
> > I am not using file systems with large folios as neither erofs(compressed files)
>
> Side note:  I will offically support large folios of compressed files
> upstream in the upcoming one or two cycle, it's almost okay in the current
> codebase.

Thanks for passing along this fantastic news! Feel free to reach me when you
send the patchset. I'm eager to delve into the code and run some tests.

>
> I have to do more tests to ensure it doesn't break anything...
>
> Thanks,
> Gao Xiang
>
> > nor f2fs supports large folios. So, yes, the page cache is full of small folios.
> >
> >>
> >> Also, do you have CONFIG_COMPACTION enabled?
> >>
> >
> > Yes. COMPACTION is enabled.
> >
Thanks
Barry