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

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2024/5/16 14:57, Barry Song wrote:
> 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.

Okay, I will cc you after I sort them out later.

Thanks,
Gao Xiang

> 
>>
>> 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