From: Aaron Lu <aaron.lwe@gmail.com>
To: Joonsoo Kim <js1304@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
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
Subject: Re: [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list
Date: Fri, 28 Feb 2020 13:57:26 +0800 [thread overview]
Message-ID: <20200228055726.GA674737@ziqianlu-desktop.localdomain> (raw)
In-Reply-To: <20200228040214.GA21040@js1304-desktop>
On Fri, Feb 28, 2020 at 01:03:03PM +0900, Joonsoo Kim wrote:
> Hello,
>
> On Fri, Feb 28, 2020 at 11:23:58AM +0800, Aaron Lu wrote:
> > On Thu, Feb 27, 2020 at 08:48:06AM -0500, Johannes Weiner wrote:
> > > On Wed, Feb 26, 2020 at 07:39:42PM -0800, Andrew Morton 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
> >
> > test: swap-w-rand-mt, which is a multi thread swap write intensive
> > workload so there will be swap out and swap ins.
> >
> > > first two patches allow the VM to usher those pages in and out of
> >
> > Weird part is, the robot says the performance gain comes from the 1st
> > patch only, which adjust the ratio, not including the 2nd patch which
> > makes anon page starting from inactive list.
> >
> > I find the performance gain hard to explain...
>
> Let me explain the reason of the performance gain.
>
> 1st patch provides more second chance to the anonymous pages.
By second chance, do I understand correctely this refers to pages on
inactive list get moved back to active list?
> In swap-w-rand-mt test, memory used by all threads is greater than the
> amount of the system memory, but, memory used by each thread would
> not be much. So, although it is a rand test, there is a locality
> in each thread's job. More second chance helps to exploit this
> locality so performance could be improved.
Does this mean there should be fewer vmstat.pswpout and vmstat.pswpin
with patch1 compared to vanilla?
Thanks.
next prev parent reply other threads:[~2020-02-28 5:57 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
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 [this message]
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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