Thread (58 messages) 58 messages, 8 authors, 2025-10-28

Re: [PATCH v3 13/13] mm: introduce arch_wants_lazy_mmu_mode()

From: Kevin Brodsky <hidden>
Date: 2025-10-24 12:17:31
Also in: linux-arm-kernel, linux-mm, lkml, sparclinux, xen-devel

On 23/10/2025 22:10, David Hildenbrand wrote:
On 15.10.25 10:27, Kevin Brodsky wrote:
quoted
powerpc decides at runtime whether the lazy MMU mode should be used.

To avoid the overhead associated with managing
task_struct::lazy_mmu_state if the mode isn't used, introduce
arch_wants_lazy_mmu_mode() and bail out of lazy_mmu_mode_* if it
returns false. Add a default definition returning true, and an
appropriate implementation for powerpc.

Signed-off-by: Kevin Brodsky <redacted>
---
This patch seemed like a good idea to start with, but now I'm not so
sure that the churn added to the generic layer is worth it.
Exactly my thoughts :)

I think we need evidence that this is really worth it for optimizing
out basically a counter update on powerpc.
Ack, I'll drop that patch in v4 unless someone sees a better
justification for it.

- Kevin
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