linux-kernel - Re: [PATCH mm-unstable v15 08/14] mm: multi-gen LRU: support page table walks

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Date:   Wed, 28 Sep 2022 13:36:58 -0600
From:   Yu Zhao <yuzhao@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Aneesh Kumar <aneesh.kumar@...ux.ibm.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Hillf Danton <hdanton@...a.com>, Jens Axboe <axboe@...nel.dk>,
        Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Mel Gorman <mgorman@...e.de>,
        Michael Larabel <Michael@...haellarabel.com>,
        Michal Hocko <mhocko@...nel.org>,
        Mike Rapoport <rppt@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>, Vlastimil Babka <vbabka@...e.cz>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        page-reclaim@...gle.com, Brian Geffon <bgeffon@...gle.com>,
        Jan Alexander Steffens <heftig@...hlinux.org>,
        Oleksandr Natalenko <oleksandr@...alenko.name>,
        Steven Barrett <steven@...uorix.net>,
        Suleiman Souhlal <suleiman@...gle.com>,
        Daniel Byrne <djbyrne@....edu>,
        Donald Carr <d@...os-reins.com>,
        Holger Hoffstätte 
        <holger@...lied-asynchrony.com>,
        Konstantin Kharlamov <Hi-Angel@...dex.ru>,
        Shuang Zhai <szhai2@...rochester.edu>,
        Sofia Trinh <sofia.trinh@....works>,
        Vaibhav Jain <vaibhav@...ux.ibm.com>
Subject: Re: [PATCH mm-unstable v15 08/14] mm: multi-gen LRU: support page
 table walks

Hi Andrew,

Can you please take another fixlet? Thanks.

Don't sync disk for each aging cycle.

wakeup_flusher_threads() was added under the assumption that if a
system runs out of clean cold pages, it might want to write back dirty
pages more aggressively so that they can become clean and be dropped.

However, doing so can breach the rate limit a system wants to impose
on writeback, resulting in early SSD wearout.

Reported-by: Axel Rasmussen <axelrasmussen@...gle.com>
Signed-off-by: Yu Zhao <yuzhao@...gle.com>
---
 mm/vmscan.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5b565470286b..0317d4cf4884 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4413,8 +4413,6 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
 	if (wq_has_sleeper(&lruvec->mm_state.wait))
 		wake_up_all(&lruvec->mm_state.wait);
 
-	wakeup_flusher_threads(WB_REASON_VMSCAN);
-
 	return true;
 }
 
-- 
2.37.3.998.g577e59143f-goog