On 28.02.25 03:51, Linus Torvalds wrote:
On Thu, 27 Feb 2025 at 18:31, Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> wrote:
This series introduces SKSM, a new page deduplication ABI,
aiming to fix the limitations inherent to the KSM ABI.
So I'm not interested in seeing *another* KSM version.
Because I absolutely do *NOT* want a new chapter in the saga of SLUB
vs SLAB vs SLOB.
However, if the feeling is that this can *replace* the current horror
that is KSM, I'm a lot more interested. I suspect our current KSM
model has largely been a failure, and this might be "good enough".
Maybe it would be comparable to khugepaged vs. MADV_COLLAPSE?
Many/most use cases just leave THP scanning+collapsing to khugepaged;
selected ones might "know better" what to do, so they effectively
disable khugepaged, and manually collapse THPs using MADV_COLLAPSE.
If it would be similar to that, it would not be completely different KSM
version, just a different way to trigger merging: background scanning
vs. user-space triggered ("synchronous").
I could see use cases for such a synchronous interface, but I doubt it
could replace the background scanning that is actively getting used for
existing use cases; I have similar thoughts about khugepaged vs.
MADV_COLLAPSE.
--
Cheers,
David / dhildenb
