Re: [RFC PATCH v12 00/26] LUF(Lazy Unmap Flush) reducing tlb numbers over 90%

Shakeel Butt
2025-02-22T01:15:00Z

On Thu, Feb 20, 2025 at 04:29:51PM +0100, Vlastimil Babka wrote:
> On 2/20/25 16:15, Dave Hansen wrote:
> > On 2/19/25 21:20, Byungchul Park wrote:
> >> I'm posting the latest version so that anyone can try luf mechanism if
> >> wanted by any chance. However, I tagged RFC again because there are
> >> still issues that should be resolved to merge to mainline:
> >
> > I don't see anything fundamentally different here from the last 11
> > versions. I think the entire approach is dangerous and basically makes
> > things impossible to debug. It's not clear that some of the failure
> > scenarios that I've brought up in the past have actually been fixed.
>
> Yes, and it's still an invasive change to the buddy allocator.
> IIRC at Plumbers the opinion in the audience was that there might be ways to
> improve the batching on unmap to reduce the flushes without such an invasive
> and potentially dangerous change? Has that been investigated?
>

I know SJ (CCed) is working on making TLB flush batching work for
process_madvise().