On 08.03.24 14:45, Ryan Roberts wrote:
On 08/03/2024 13:24, David Hildenbrand wrote:
This patch migrates the last subpage to a small folio and immediately
returns the large folio to the system. It benefits both memory availability
and anti-fragmentation.
It might be controversial optimization, and as Ryan said, there, are likely
other cases where we'd want to migrate off-of a thp if possible earlier.
Personally, I think there might also be cases where you want to copy/reuse the
entire large folio. If you're application is using 16K THPs perhaps it's a
bigger win to just treat it like a base page? I expect the cost/benefit will
change as the THP size increases?
Yes, I think for small folios (i.e., 16KiB) it will be rather easy to make a
decision. The larger the folio, the larger the page fault latency due to
scanning, copying, modifying, which can easily turn undesirable.
At least when it comes to page reuse, I have some simple backup plans for small
folios if I won't be able to make progress with my other approach.
Do you mean "small large folios" here? i.e. order >= 1? If so, great!
*smaller*, yes :)
--
Cheers,
David / dhildenb
