On 26.09.21 18:12, Nadav Amit wrote:
From: Nadav Amit <namit@xxxxxxxxxx> The goal of these patches is to add support for process_madvise(MADV_DONTNEED). Yet, in the process some (arguably) useful cleanups, a bug fix and performance enhancements are performed. The patches try to consolidate the logic across different behaviors, and to a certain extent overlap/conflict with an outstanding patch that does something similar [1]. This consolidation however is mostly orthogonal to the aforementioned one and done in order to clarify what is done in respect to locks and TLB for each behavior and to batch these operations more efficiently on process_madvise(). process_madvise(MADV_DONTNEED) is useful for two reasons: (a) it allows userfaultfd monitors to unmap memory from monitored processes; and (b) it is more efficient than madvise() since it is vectored and batches TLB flushes more aggressively.
MADV_DONTNEED on MAP_PRIVATE memory is a target-visible operation; this is very different to all the other process_madvise() calls we allow, which are merely hints, but the target cannot be broken . I don't think this is acceptable.
-- Thanks, David / dhildenb
