From: Christoph Lameter <cl@linux.com>
To: Will Deacon <will@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Vincent Guittot <vincent.guittot@linaro.org>,
Bharata B Rao <bharata@linux.ibm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
guro@fb.com, Shakeel Butt <shakeelb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
aneesh.kumar@linux.ibm.com, Jann Horn <jannh@google.com>,
Michal Hocko <mhocko@kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>
Subject: Re: [RFC PATCH v0] mm/slub: Let number of online CPUs determine the slub page order
Date: Wed, 27 Jan 2021 09:10:14 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2101270907260.673600@www.lameter.com> (raw)
In-Reply-To: <20210126230305.GD30941@willie-the-truck>
On Tue, 26 Jan 2021, Will Deacon wrote:
> > Hm, but booting the secondaries is just a software (kernel) action? They are
> > already physically there, so it seems to me as if the cpu_present_mask is not
> > populated correctly on arm64, and it's just a mirror of cpu_online_mask?
>
> I think the present_mask retains CPUs if they are hotplugged off, whereas
> the online mask does not. We can't really do any better on arm64, as there's
> no way of telling that a CPU is present until we've seen it.
The order of each page in a kmem cache --and therefore also the number
of objects in a slab page-- can be different because that information is
stored in the page struct.
Therefore it is possible to retune the order while the cache is in operaton.
This means you can run an initcall after all cpus have been brought up to
set the order and number of objects in a slab page differently.
The older slab pages will continue to exist with the old orders until they
are freed.
next prev parent reply other threads:[~2021-01-27 9:15 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 8:27 [RFC PATCH v0] mm/slub: Let number of online CPUs determine the slub page order Bharata B Rao
2020-11-18 11:25 ` Vlastimil Babka
2020-11-18 19:34 ` Roman Gushchin
2020-11-18 19:53 ` David Rientjes
2020-11-18 19:53 ` David Rientjes
2021-01-20 17:36 ` Vincent Guittot
2021-01-20 17:36 ` Vincent Guittot
2021-01-21 5:30 ` Bharata B Rao
2021-01-21 9:09 ` Vincent Guittot
2021-01-21 9:09 ` Vincent Guittot
2021-01-21 10:01 ` Christoph Lameter
2021-01-21 10:01 ` Christoph Lameter
2021-01-21 10:48 ` Vincent Guittot
2021-01-21 10:48 ` Vincent Guittot
2021-01-21 18:19 ` Vlastimil Babka
2021-01-22 8:03 ` Vincent Guittot
2021-01-22 8:03 ` Vincent Guittot
2021-01-22 12:03 ` Vlastimil Babka
2021-01-22 13:16 ` Vincent Guittot
2021-01-22 13:16 ` Vincent Guittot
2021-01-23 5:16 ` Bharata B Rao
2021-01-23 12:32 ` Vincent Guittot
2021-01-23 12:32 ` Vincent Guittot
2021-01-25 11:20 ` Vlastimil Babka
2021-01-26 23:03 ` Will Deacon
2021-01-27 9:10 ` Christoph Lameter [this message]
2021-01-27 9:10 ` Christoph Lameter
2021-01-27 11:04 ` Vlastimil Babka
2021-02-03 11:10 ` Bharata B Rao
2021-02-04 7:32 ` Vincent Guittot
2021-02-04 7:32 ` Vincent Guittot
2021-02-04 9:07 ` Christoph Lameter
2021-02-04 9:07 ` Christoph Lameter
2021-02-04 9:33 ` Vlastimil Babka
2021-02-08 13:41 ` [PATCH] mm, slub: better heuristic for number of cpus when calculating slab order Vlastimil Babka
2021-02-08 14:54 ` Vincent Guittot
2021-02-08 14:54 ` Vincent Guittot
2021-02-10 14:07 ` Mel Gorman
2021-01-22 13:05 ` [RFC PATCH v0] mm/slub: Let number of online CPUs determine the slub page order Jann Horn
2021-01-22 13:05 ` Jann Horn
2021-01-22 13:09 ` Jann Horn
2021-01-22 13:09 ` Jann Horn
2021-01-22 15:27 ` Vlastimil Babka
2021-01-25 4:28 ` Bharata B Rao
2021-01-26 8:52 ` Michal Hocko
2021-01-26 13:38 ` Vincent Guittot
2021-01-26 13:38 ` Vincent Guittot
2021-01-26 13:59 ` Michal Hocko
2021-01-27 13:38 ` Vlastimil Babka
2021-01-28 13:45 ` Mel Gorman
2021-01-28 13:57 ` Michal Hocko
2021-01-28 14:42 ` Mel Gorman
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