From: Joonsoo Kim <js1304@gmail.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <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 v4 8/8] mm/swap: count a new anonymous page as a reclaim_state's rotate
Date: Tue, 24 Mar 2020 15:28:36 +0900 [thread overview]
Message-ID: <CAAmzW4Mts-EbsYGWbdJyAR01dsoVNR4OYbRDCxfp_eD_p4fD0w@mail.gmail.com> (raw)
In-Reply-To: <20200323174257.GF204561@cmpxchg.org>
2020년 3월 24일 (화) 오전 2:43, Johannes Weiner <hannes@cmpxchg.org>님이 작성:
>
> On Mon, Mar 23, 2020 at 02:52:12PM +0900, js1304@gmail.com wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > reclaim_stat's rotate is used for controlling the ratio of scanning page
> > between file and anonymous LRU. All new anonymous pages are counted
> > for rotate before the patch, protecting anonymous pages on active LRU, and,
> > it makes that reclaim on anonymous LRU is less happened than file LRU.
> >
> > Now, situation is changed. all new anonymous pages are not added
> > to the active LRU so rotate would be far less than before. It will cause
> > that reclaim on anonymous LRU happens more and it would result in bad
> > effect on some system that is optimized for previous setting.
> >
> > Therefore, this patch counts a new anonymous page as a reclaim_state's
> > rotate. Although it is non-logical to add this count to
> > the reclaim_state's rotate in current algorithm, reducing the regression
> > would be more important.
> >
> > I found this regression on kernel-build test and it is roughly 2~5%
> > performance degradation. With this workaround, performance is completely
> > restored.
> >
> > v2: fix a bug that reuses the rotate value for previous page
>
> I agree with the rationale, but the magic bit in the page->lru list
> pointers seems pretty ugly.
Yes, pretty ugly.
> I wrote a patch a few years ago that split lru_add_pvecs into an add
> and a putback component. This was to avoid unintentional balancing
> effects of LRU isolations, but I think you can benefit from that
> cleanup here as well. Would you mind taking a look at it and maybe
> take it up into your series?
>
> https://lore.kernel.org/patchwork/patch/685708/
Thanks for pointing that.
I will remove the magic bit and imitate your patch to solve the problem
of this patch.
Thanks.
prev parent reply other threads:[~2020-03-24 6:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 5:52 [PATCH v4 0/8] workingset protection/detection on the anonymous LRU list js1304
2020-03-23 5:52 ` [PATCH v4 1/8] mm/vmscan: make active/inactive ratio as 1:1 for anon lru js1304
2020-03-23 5:52 ` [PATCH v4 2/8] mm/vmscan: protect the workingset on anonymous LRU js1304
2020-03-23 5:52 ` [PATCH v4 3/8] mm/workingset: extend the workingset detection for anon LRU js1304
2020-03-23 5:52 ` [PATCH v4 4/8] mm/swapcache: support to handle the exceptional entries in swapcache js1304
2020-03-23 16:50 ` Johannes Weiner
2020-03-23 5:52 ` [PATCH v4 5/8] mm/workingset: handle the page without memcg js1304
2020-03-23 16:51 ` Johannes Weiner
2020-03-23 5:52 ` [PATCH v4 6/8] mm/swap: implement workingset detection for anonymous LRU js1304
2020-03-23 17:17 ` Johannes Weiner
2020-03-24 6:25 ` Joonsoo Kim
2020-04-02 5:50 ` Joonsoo Kim
2020-04-02 15:14 ` Johannes Weiner
2020-03-23 5:52 ` [PATCH v4 7/8] mm/vmscan: restore active/inactive ratio " js1304
2020-03-23 17:18 ` Johannes Weiner
2020-03-23 5:52 ` [PATCH v4 8/8] mm/swap: count a new anonymous page as a reclaim_state's rotate js1304
2020-03-23 17:42 ` Johannes Weiner
2020-03-24 6:28 ` Joonsoo Kim [this message]
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