Re: [RFC PATCH 12/13] fs/userfaultfd: kmem-cache for wait-queue objects

[Nadav Amit]

> On Nov 28, 2020, at 4:45 PM, Nadav Amit <nadav.amit@xxxxxxxxx> wrote:
> 
> From: Nadav Amit <namit@xxxxxxxxxx>
> 
> Allocating work-queue objects on the stack has usually negative
> performance side-effects. First, it is hard to ensure alignment to
> cache-lines without increasing the stack size. Second, it might cause
> false sharing. Third, it is more likely to encounter TLB misses as
> objects are more likely reside on different pages.
> 
> Allocate userfaultfd wait-queue objects on the heap using kmem-cache for
> better performance.

Err… The wait-queue objects are still on the stack in some cases that I
missed. Will fix.