linux-kernel - Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to make progress

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Date:   Wed, 1 Dec 2021 01:03:48 +0900
From:   Alexey Avramov <hakavlad@...ox.lv>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Rik van Riel <riel@...riel.com>,
        Mike Galbraith <efault@....de>,
        Darrick Wong <djwong@...nel.org>, regressions@...ts.linux.dev,
        Linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to
 make progress

I tested this [1] patch on top of 5.16-rc2. It's the same test with 10 tails.

- with noswap

Summary:

2021-11-30 23:32:36,890: Stall times for the last 548.6s:
2021-11-30 23:32:36,890: -----------
2021-11-30 23:32:36,891: some cpu     3.7s, avg 0.7%
2021-11-30 23:32:36,891: -----------
2021-11-30 23:32:36,891: some io      187.6s, avg 34.2%
2021-11-30 23:32:36,891: full io      178.3s, avg 32.5%
2021-11-30 23:32:36,891: -----------
2021-11-30 23:32:36,892: some memory  392.2s, avg 71.5%
2021-11-30 23:32:36,892: full memory  390.7s, avg 71.2%

full psi:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/noswap/psi

mem:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/noswap/mem

- with swappiness=0

Summary:

2021-11-30 23:51:48,969: Stall times for the last 919.4s:
2021-11-30 23:51:48,969: -----------
2021-11-30 23:51:48,969: some cpu     5.5s, avg 0.6%
2021-11-30 23:51:48,970: -----------
2021-11-30 23:51:48,970: some io      240.4s, avg 26.2%
2021-11-30 23:51:48,970: full io      230.6s, avg 25.1%
2021-11-30 23:51:48,970: -----------
2021-11-30 23:51:48,970: some memory  806.1s, avg 87.7%
2021-11-30 23:51:48,971: full memory  800.5s, avg 87.1%

psi log:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/swappiness0/psi

mem log:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/swappiness0/mem

In some cases stalls was very short, but in many cases stalls was long. 
The result is still not good enough.


offtop
======

The same test with the patch [1] on top of 5.16-rc2 + le9 patch [2] 
with vm.clean_min_kbytes=99000.

- with noswap

Summary:

2021-11-30 23:59:32,209: Stall times for the last 73.1s:
2021-11-30 23:59:32,209: -----------
2021-11-30 23:59:32,209: some cpu     0.4s, avg 0.5%
2021-11-30 23:59:32,209: -----------
2021-11-30 23:59:32,210: some io      5.8s, avg 8.0%
2021-11-30 23:59:32,210: full io      5.3s, avg 7.3%
2021-11-30 23:59:32,210: -----------
2021-11-30 23:59:32,210: some memory  3.3s, avg 4.5%
2021-11-30 23:59:32,210: full memory  3.1s, avg 4.2%

This is just an example of what a result close to the expected 
result might be (especially note io pressure values).

full psi:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/noswap_le9_min99k/psi

mem:
https://raw.githubusercontent.com/hakavlad/cache-tests/main/516-reclaim-throttle/516-rc2/patch5/noswap_le9_min99k/mem

[1] https://lore.kernel.org/lkml/20211129150117.GO3366@techsingularity.net/
[2] https://lore.kernel.org/all/20211130201652.2218636d@mail.inbox.lv/