From: Yu Zhao <yuzhao@google.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Andi Kleen" <ak@linux.intel.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Hillf Danton" <hdanton@sina.com>, "Jens Axboe" <axboe@kernel.dk>,
"Jesse Barnes" <jsbarnes@google.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Matthew Wilcox" <willy@infradead.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Larabel" <Michael@michaellarabel.com>,
"Michal Hocko" <mhocko@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"Rik van Riel" <riel@surriel.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
"Ying Huang" <ying.huang@intel.com>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"Kernel Page Reclaim v2" <page-reclaim@google.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Brian Geffon" <bgeffon@google.com>,
"Jan Alexander Steffens" <heftig@archlinux.org>,
"Oleksandr Natalenko" <oleksandr@natalenko.name>,
"Steven Barrett" <steven@liquorix.net>,
"Suleiman Souhlal" <suleiman@google.com>,
"Daniel Byrne" <djbyrne@mtu.edu>,
"Donald Carr" <d@chaos-reins.com>,
"Holger Hoffstätte" <holger@applied-asynchrony.com>,
"Konstantin Kharlamov" <Hi-Angel@yandex.ru>,
"Shuang Zhai" <szhai2@cs.rochester.edu>,
"Sofia Trinh" <sofia.trinh@edi.works>,
"Vaibhav Jain" <vaibhav@linux.ibm.com>
Subject: Re: [PATCH v9 06/14] mm: multi-gen LRU: minimal implementation
Date: Mon, 21 Mar 2022 22:02:57 -0600 [thread overview]
Message-ID: <CAOUHufa1nuyJ1MawqBTRZS78EFOGTw0_qh5k3XvDo9XQCvan7g@mail.gmail.com> (raw)
In-Reply-To: <87czif79k2.fsf@linux.ibm.com>
On Mon, Mar 21, 2022 at 6:52 AM Aneesh Kumar K.V
<aneesh.kumar@linux.ibm.com> wrote:
>
> +
> > +static long get_nr_evictable(struct lruvec *lruvec, unsigned long max_seq,
> > + unsigned long *min_seq, bool can_swap, bool *need_aging)
> > +{
> > + int gen, type, zone;
> > + long old = 0;
> > + long young = 0;
> > + long total = 0;
> > + struct lru_gen_struct *lrugen = &lruvec->lrugen;
> > +
> > + for (type = !can_swap; type < ANON_AND_FILE; type++) {
> > + unsigned long seq;
> > +
> > + for (seq = min_seq[type]; seq <= max_seq; seq++) {
> > + long size = 0;
> > +
> > + gen = lru_gen_from_seq(seq);
> > +
> > + for (zone = 0; zone < MAX_NR_ZONES; zone++)
> > + size += READ_ONCE(lrugen->nr_pages[gen][type][zone]);
> > +
> > + total += size;
> > + if (seq == max_seq)
> > + young += size;
> > + if (seq + MIN_NR_GENS == max_seq)
> > + old += size;
> > + }
> > + }
> > +
> > + /* try to spread pages out across MIN_NR_GENS+1 generations */
> > + if (min_seq[LRU_GEN_FILE] + MIN_NR_GENS > max_seq)
> > + *need_aging = true;
> > + else if (min_seq[LRU_GEN_FILE] + MIN_NR_GENS < max_seq)
> > + *need_aging = false;
>
> Can you explain/document the reason for the considering the below
> conditions for ageing?
>
> > + else if (young * MIN_NR_GENS > total)
> > + *need_aging = true;
>
> Are we trying to consdier the case of more than half the total pages
> young as needing ageing? If so should MIN_NR_GENS be 2 instead of using
> that #define? Or
>
> > + else if (old * (MIN_NR_GENS + 2) < total)
> > + *need_aging = true;
>
> What is the significance of '+ 2' ?
Will improve the comment according to my previous reply here [1].
[1] https://lore.kernel.org/linux-mm/CAOUHufYmUPZY0gCC+wYk6Vr1L8KEx+tJeEAhjpBfUnLJsAHq5A@mail.gmail.com/
next prev parent reply other threads:[~2022-03-22 4:03 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-09 2:12 [PATCH v9 00/14] Multi-Gen LRU Framework Yu Zhao
2022-03-09 2:12 ` [PATCH v9 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-03-11 10:55 ` Barry Song
2022-03-11 22:57 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-03-16 22:15 ` Barry Song
2022-03-09 2:12 ` [PATCH v9 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-03-18 1:15 ` Barry Song
2022-03-09 2:12 ` [PATCH v9 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao
2022-03-09 2:12 ` [PATCH v9 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-03-14 8:08 ` Huang, Ying
2022-03-14 9:30 ` Yu Zhao
2022-03-15 0:34 ` Huang, Ying
2022-03-15 0:50 ` Yu Zhao
2022-03-21 18:58 ` Justin Forbes
2022-03-21 19:17 ` Prarit Bhargava
2022-03-22 4:52 ` Yu Zhao
2022-03-16 23:25 ` Barry Song
2022-03-21 9:04 ` Yu Zhao
2022-03-21 11:47 ` Barry Song
2022-03-09 2:12 ` [PATCH v9 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-03-16 5:55 ` Huang, Ying
2022-03-16 7:54 ` Yu Zhao
2022-03-19 3:01 ` Barry Song
2022-03-19 3:11 ` Yu Zhao
2022-03-23 7:47 ` Barry Song
2022-03-24 6:24 ` Yu Zhao
2022-03-24 8:13 ` Barry Song
2022-03-19 10:14 ` Barry Song
2022-03-21 23:51 ` Yu Zhao
2022-03-19 11:15 ` Barry Song
2022-03-22 0:30 ` Yu Zhao
2022-03-21 12:51 ` Aneesh Kumar K.V
2022-03-22 4:02 ` Yu Zhao [this message]
2022-03-21 13:01 ` Aneesh Kumar K.V
2022-03-22 4:39 ` Yu Zhao
2022-03-22 5:26 ` Aneesh Kumar K.V
2022-03-22 5:55 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao
2022-04-07 2:29 ` Barry Song
2022-04-07 3:04 ` Yu Zhao
2022-04-07 3:46 ` Barry Song
2022-04-07 23:51 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 08/14] mm: multi-gen LRU: support page table walks Yu Zhao
2022-03-09 2:12 ` [PATCH v9 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao
2022-03-09 2:12 ` [PATCH v9 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-03-22 7:47 ` Barry Song
2022-03-22 8:20 ` Yu Zhao
2022-03-22 8:45 ` Barry Song
2022-03-22 9:00 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao
2022-03-22 7:22 ` Barry Song
2022-03-22 8:14 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-03-09 2:12 ` [PATCH v9 13/14] mm: multi-gen LRU: admin guide Yu Zhao
2022-03-10 12:29 ` Mike Rapoport
2022-03-11 0:37 ` Yu Zhao
2022-03-09 2:12 ` [PATCH v9 14/14] mm: multi-gen LRU: design doc Yu Zhao
2022-03-11 8:22 ` Mike Rapoport
2022-03-11 9:38 ` Yu Zhao
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