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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, Huang Ying <ying.huang@intel.com>
Subject: Re: [PATCH v2 0/9] workingset protection/detection on the anonymous LRU list
Date: Fri, 28 Feb 2020 18:21:45 +0800	[thread overview]
Message-ID: <20200228102145.GA675897@ziqianlu-desktop.localdomain> (raw)
In-Reply-To: <20200228095534.GA30796@js1304-desktop>

On Fri, Feb 28, 2020 at 06:56:11PM +0900, Joonsoo Kim wrote:
> On Fri, Feb 28, 2020 at 05:17:00PM +0800, Aaron Lu wrote:
> > I think LKP robot has captured these two metrics but the report didn't
> > show them, which means the number is about the same with or without
> > patch #1.
> 
> robot showed these two metrics. See below.
> 
>   50190319 ± 31%     -35.7%   32291856 ± 14%  proc-vmstat.pswpin
>   56429784 ± 21%     -42.6%   32386842 ± 14%  proc-vmstat.pswpout
> 
> pswpin/out are improved.

Oh yes, I checked the vmstat part, while I should check proc-vmstat
part...Sorry for missing this.

> 
> > > with patch #1. With large inactive list, we can easily find the
> > > frequently referenced page and it would result in less swap in/out.
> > 
> > But with small inactive list, the pages that would be on inactive list
> > will stay on active list? I think the larger inactive list is mainly
> > used to give the anon page a chance to be promoted to active list now
> > that anon pages land on inactive list first, but on reclaim, I don't see
> > how a larger inactive list can cause fewer swap outs.
> 
> Point is that larger inactive LRU helps to find hot pages and these
> hot pages leads to more cache hits.
> 
> When a cache hit happens, no swap outs happens. But, if a cache miss
> happens, a new page is added to the LRU and then it causes the reclaim
> and swap out.

OK, I think I start to get your point. Your explanation makes sense.

> > Forgive me for my curiosity and feel free to ignore my question as I
> > don't want to waste your time on this. Your patchset looks a worthwhile
> > thing to do, it's just the robot's report on patch1 seems er...
> 
> I appreciate your attention. Feel free to ask. :)

Thanks a lot for your patience and nice explanation :-)


      reply	other threads:[~2020-02-28 10:21 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20  5:11 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
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 [this message]

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