Re: [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list

Joonsoo Kim
2020-03-11T07:27:58Z

2020년 3월 3일 (화) 오전 8:31, Joonsoo Kim <js1304@gmail.com>님이 작성:
>
> 2020년 2월 28일 (금) 오전 8:36, Andrew Morton <akpm@linux-foundation.org>님이 작성:
> >
> > On Thu, 27 Feb 2020 08:48:06 -0500 Johannes Weiner <hannes@cmpxchg.org> wrote:
> >
> > > > It sounds like the above simple aging changes provide most of the
> > > > improvement, and that the workingset changes are less beneficial and a
> > > > bit more risky/speculative?
> > > >
> > > > If so, would it be best for us to concentrate on the aging changes
> > > > first, let that settle in and spread out and then turn attention to the
> > > > workingset changes?
> > >
> > > Those two patches work well for some workloads (like the benchmark),
> > > but not for others. The full patchset makes sure both types work well.
> > >
> > > Specifically, the existing aging strategy for anon assumes that most
> > > anon pages allocated are hot. That's why they all start active and we
> > > then do second-chance with the small inactive LRU to filter out the
> > > few cold ones to swap out. This is true for many common workloads.
> > >
> > > The benchmark creates a larger-than-memory set of anon pages with a
> > > flat access profile - to the VM a flood of one-off pages. Joonsoo's
> > > first two patches allow the VM to usher those pages in and out of
> > > memory very quickly, which explains the throughput boost. But it comes
> > > at the cost of reducing space available to hot anon pages, which will
> > > regress others.
> > >
> > > Joonsoo's full patchset makes the VM support both types of workloads
> > > well: by putting everything on the inactive list first, one-off pages
> > > can move through the system without disturbing the hot pages. And by
> > > supplementing the inactive list with non-resident information, he can
> > > keep it tiny without the risk of one-off pages drowning out new hot
> > > pages. He can retain today's level of active page protection and
> > > detection, while allowing one-off pages to move through quickly.
> >
> > Helpful, thanks.
> >
> > At v2 with no evident review input I'd normally take a pass at this
> > stage. But given all the potential benefits, perhaps I should be more
> > aggressive here?
>
> I hope so. It would boost the review. :)

Hello, Andrew.

Would you like to tell me your plan about this patchset?
Merging it into the next tree would accelerate the review and test. :)

Thanks.