From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Pavel Tatashin <pasha.tatashin@soleen.com>,
David Hildenbrand <david@redhat.com>,
Oscar Salvador <osalvador@suse.de>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 3/9] mm, page_alloc: remove setup_pageset()
Date: Wed, 7 Oct 2020 00:11:32 +0200 [thread overview]
Message-ID: <2e6c56aa-a8b0-2d10-eca1-4138424d2db3@suse.cz> (raw)
In-Reply-To: <20201005125946.GY4555@dhcp22.suse.cz>
On 10/5/20 2:59 PM, Michal Hocko wrote:
> On Tue 22-09-20 16:37:06, Vlastimil Babka wrote:
>> We initialize boot-time pagesets with setup_pageset(), which sets high and
>> batch values that effectively disable pcplists.
>>
>> We can remove this wrapper if we just set these values for all pagesets in
>> pageset_init(). Non-boot pagesets then subsequently update them to the proper
>> values.
>>
>> No functional change.
>>
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>> ---
>> mm/page_alloc.c | 17 ++++++++++-------
>> 1 file changed, 10 insertions(+), 7 deletions(-)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 26069c8d1b19..76c2b4578723 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -5823,7 +5823,7 @@ static void build_zonelists(pg_data_t *pgdat)
>> * not check if the processor is online before following the pageset pointer.
>> * Other parts of the kernel may not check if the zone is available.
>> */
>> -static void setup_pageset(struct per_cpu_pageset *p);
>> +static void pageset_init(struct per_cpu_pageset *p);
>> static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
>> static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
>>
>> @@ -5891,7 +5891,7 @@ build_all_zonelists_init(void)
>> * (a chicken-egg dilemma).
>> */
>> for_each_possible_cpu(cpu)
>> - setup_pageset(&per_cpu(boot_pageset, cpu));
>> + pageset_init(&per_cpu(boot_pageset, cpu));
>>
>> mminit_verify_zonelist();
>> cpuset_init_current_mems_allowed();
>> @@ -6210,12 +6210,15 @@ static void pageset_init(struct per_cpu_pageset *p)
>> pcp = &p->pcp;
>> for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
>> INIT_LIST_HEAD(&pcp->lists[migratetype]);
>> -}
>>
>> -static void setup_pageset(struct per_cpu_pageset *p)
>> -{
>> - pageset_init(p);
>> - pageset_update(&p->pcp, 0, 1);
>> + /*
>> + * Set batch and high values safe for a boot pageset. A true percpu
>> + * pageset's initialization will update them subsequently. Here we don't
>> + * need to be as careful as pageset_update() as nobody can access the
>> + * pageset yet.
>
> Isn't this slightly misleading? pageset_init is called from setup_zone_pageset
> which is called from the memory hotplug as well. Isn't this more about
It is.
> early zone initialization rather than boot pagesets? Or am I misreading
> the patch?
It's for boot pagesets (call from build_all_zonelists_init()) that we need these
particular values (well, just high = 0). For early zone initialization during
hotplug the values don't matter as the caller is setup_zone_pageset() who
immediately replaces the values by zone_set_pageset_high_and_batch(). Which is
what the comment tries to say.
>> + */
>> + pcp->high = 0;
>> + pcp->batch = 1;
>> }
>>
>> /*
>> --
>> 2.28.0
>
next prev parent reply other threads:[~2020-10-06 22:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 14:37 [PATCH 0/9] disable pcplists during memory offline Vlastimil Babka
2020-09-22 14:37 ` [PATCH 1/9] mm, page_alloc: clean up pageset high and batch update Vlastimil Babka
2020-09-25 10:18 ` David Hildenbrand
2020-10-05 12:03 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 2/9] mm, page_alloc: calculate pageset high and batch once per zone Vlastimil Babka
2020-10-05 12:52 ` Michal Hocko
2020-10-06 22:04 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 3/9] mm, page_alloc: remove setup_pageset() Vlastimil Babka
2020-09-25 10:19 ` David Hildenbrand
2020-10-05 12:59 ` Michal Hocko
2020-10-06 22:11 ` Vlastimil Babka [this message]
2020-09-22 14:37 ` [PATCH 4/9] mm, page_alloc: simplify pageset_update() Vlastimil Babka
2020-09-25 10:23 ` David Hildenbrand
2020-10-05 13:20 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 5/9] mm, page_alloc: make per_cpu_pageset accessible only after init Vlastimil Babka
2020-09-25 10:25 ` David Hildenbrand
2020-10-05 13:24 ` Michal Hocko
2020-10-06 22:28 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 6/9] mm, page_alloc: cache pageset high and batch in struct zone Vlastimil Babka
2020-09-25 10:34 ` David Hildenbrand
2020-10-06 22:31 ` Vlastimil Babka
2020-10-05 13:28 ` Michal Hocko
2020-10-06 22:34 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 7/9] mm, page_alloc: move draining pcplists to page isolation users Vlastimil Babka
2020-09-25 10:39 ` David Hildenbrand
2020-10-05 13:57 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 8/9] mm, page_alloc: drain all pcplists during memory offline Vlastimil Babka
2020-09-25 10:46 ` David Hildenbrand
2020-10-05 14:03 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 9/9] mm, page_alloc: optionally disable pcplists during page isolation Vlastimil Babka
2020-09-25 10:53 ` David Hildenbrand
2020-09-25 10:54 ` David Hildenbrand
2020-09-25 11:10 ` Vlastimil Babka
2020-10-01 8:47 ` David Hildenbrand
2020-10-05 14:05 ` Michal Hocko
2020-10-05 14:22 ` Vlastimil Babka
2020-10-05 16:56 ` Michal Hocko
2020-10-06 8:34 ` Michal Hocko
2020-10-06 8:40 ` David Hildenbrand
2020-10-06 10:05 ` Michal Hocko
2020-09-22 17:15 ` [PATCH 0/9] disable pcplists during memory offline David Hildenbrand
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