Re: [RFC PATCH 0/5] mm: support zswap-backed anonymous large folio swapin

[Fujunjie]

On 5/19/2026 10:49 PM, Alexandre Ghiti wrote:
> Hi,
> 
> On Tue, May 12, 2026 at 9:46 AM Fujunjie <fujunjie1@xxxxxx> wrote:
>>
>>>
>>
>>
>> On 5/12/2026 12:20 PM, Alexandre Ghiti wrote:
>>> So I have been working on the exact same thing for some weeks now. My work is based on Usama's series [1].
>>>
>>> The problem with large folio swapin is that it can create swap thrashing: to swap in a large folio, swap out may be necessary, as reported in [2].
>>>
>>> I implemented quite a few throttling algorithms on top to try to avoid this issue and so far, I have had mixed/inconsistent results.
>>>
>>> How did you test this series? Did you encounter thrashing? Do you have performance numbers?
>>>
>>> Happy to talk more about this, thanks for your series!
>>>
>>> Alex
>>>
>>> [1] https://lore.kernel.org/all/20241018105026.2521366-1-usamaarif642@xxxxxxxxx/  <https://lore.kernel.org/all/20241018105026.2521366-1-usamaarif642@xxxxxxxxx/ >
>>> [2] https://lore.kernel.org/all/SJ0PR11MB5678A864244B09FDE4D914EEC9402@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/  <https://lore.kernel.org/all/SJ0PR11MB5678A864244B09FDE4D914EEC9402@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ >
>>
>> Thanks Alexandre.
>>
>> My RFC only had correctness testing so far. I tested the all-zswap path
>> and fallback cases under QEMU, but I don't have bare-metal
>> performance numbers yet.
>>
>> If you are already actively working on this, I don't want to duplicate the
>> same effort. I will pause this RFC for now and wait for your series.
>>
>> After your series is posted, I will take another look and see if there is
>> anything that still needs follow-up work.
>>
>> Thanks for letting me know.
> 
> Sorry for the late answer. I took a break because of the inconsistent
> results that I had, perhaps a fresh look could help so no worries if
> you give it a try on your end.
> 
> Happy to discuss further results if you continue.
> 
> Alex


Thanks Alexandre.

That sounds good. I will take a fresh look on my side.
If I find something useful, I will discuss with you.

Best regards,
fujunjie