From: Andrew Morton <akpm@linux-foundation.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: js1304@gmail.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
Hugh Dickins <hughd@google.com>, Minchan Kim <minchan@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list
Date: Thu, 27 Feb 2020 15:36:39 -0800 [thread overview]
Message-ID: <20200227153639.951d6a42080e8d4227872e64@linux-foundation.org> (raw)
In-Reply-To: <20200227134806.GC39625@cmpxchg.org>
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?
next prev parent reply other threads:[~2020-02-27 23:36 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 5:11 [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list js1304
2020-02-20 5:11 ` [PATCH v2 1/9] mm/vmscan: make active/inactive ratio as 1:1 for anon lru js1304
2020-03-12 14:47 ` Johannes Weiner
2020-03-13 5:48 ` Joonsoo Kim
2020-02-20 5:11 ` [PATCH v2 2/9] mm/vmscan: protect the workingset on anonymous LRU js1304
2020-03-12 15:14 ` Johannes Weiner
2020-03-13 7:40 ` Joonsoo Kim
2020-03-13 19:55 ` Johannes Weiner
2020-03-16 7:05 ` Joonsoo Kim
2020-03-16 16:12 ` Johannes Weiner
2020-03-17 4:52 ` Joonsoo Kim
2020-02-20 5:11 ` [PATCH v2 3/9] mm/workingset: extend the workingset detection for anon LRU js1304
2020-02-20 5:11 ` [PATCH v2 4/9] mm/swapcache: support to handle the value in swapcache js1304
2020-02-20 5:11 ` [PATCH v2 5/9] mm/workingset: use the node counter if memcg is the root memcg js1304
2020-02-20 5:11 ` [PATCH v2 6/9] mm/workingset: handle the page without memcg js1304
2020-02-20 5:11 ` [PATCH v2 7/9] mm/swap: implement workingset detection for anonymous LRU js1304
2020-02-20 5:11 ` [PATCH v2 8/9] mm/vmscan: restore active/inactive ratio " js1304
2020-02-20 5:11 ` [PATCH v2 9/9] mm/swap: count a new anonymous page as a reclaim_state's rotate js1304
2020-02-27 3:39 ` [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list Andrew Morton
2020-02-27 7:48 ` Joonsoo Kim
2020-03-01 4:40 ` Andrew Morton
2020-02-27 13:48 ` Johannes Weiner
2020-02-27 23:36 ` Andrew Morton [this message]
2020-03-02 23:31 ` Joonsoo Kim
2020-03-11 7:27 ` Joonsoo Kim
2020-02-28 3:23 ` Aaron Lu
2020-02-28 4:03 ` Joonsoo Kim
2020-02-28 5:57 ` Aaron Lu
2020-02-28 6:52 ` Joonsoo Kim
2020-02-28 9:17 ` Aaron Lu
2020-02-28 9:56 ` Joonsoo Kim
2020-02-28 10:21 ` Aaron Lu
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