From: David Hildenbrand <david@redhat.com>
To: osalvador@suse.de, Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@kernel.org>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [RFC 0/5] disable pcplists during page isolation
Date: Wed, 9 Sep 2020 13:29:40 +0200 [thread overview]
Message-ID: <ee56072e-53be-3f3f-cd6d-d56317f15f0a@redhat.com> (raw)
In-Reply-To: <3f4bd7b0c73f59b4cd2adaad3ccc38bf@suse.de>
On 09.09.20 13:27, osalvador@suse.de wrote:
> On 2020-09-09 12:54, Vlastimil Babka wrote:
>> Thanks! I expect no performance change while no isolation is in
>> progress, as
>> there are no new tests added in alloc/free paths. During page isolation
>> there's
>> a single drain instead of once-per-pageblock, which is a benefit. But
>> the
>> pcplists are effectively disabled for the whole of online_pages(),
>> offline_pages() or alloc_contig_range(), which will affect parallel
>> page
>> allocator users. It depends on how long these operations take and how
>> heavy the
>> parallel usage is, so I have no good answers. Might be similar to the
>> current
>> periodic drain.
>
> I have seen some systems taking quite some time when offlining sections
> due to the migration of
> the respective pages not being that smooth and having do_migrate_range
> to do some spins.
> But to be fair, online_pages and offline_pages are not routines that get
> called that often, and we would be safe to assume that memory-hotplug
> operations are not constantly happening, but are rather one-offs
> operations.
>
> I am not sure about Xen and HV, IIRC Xen was using online_pages and
> offline_pages routines to do the ballooning?
No, they only add more memory blocks and online them. Memory hot(un)plug
is an expensive operation already, I don't think that's an issue.
--
Thanks,
David / dhildenb
prev parent reply other threads:[~2020-09-09 11:29 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 16:36 Vlastimil Babka
2020-09-07 16:36 ` [RFC 1/5] mm, page_alloc: clean up pageset high and batch update Vlastimil Babka
2020-09-10 8:31 ` Oscar Salvador
2020-09-10 8:34 ` Oscar Salvador
2020-09-10 10:47 ` David Hildenbrand
2020-09-17 16:05 ` Vlastimil Babka
2020-09-07 16:36 ` [RFC 2/5] mm, page_alloc: calculate pageset high and batch once per zone Vlastimil Babka
2020-09-10 9:00 ` Oscar Salvador
2020-09-10 10:56 ` David Hildenbrand
2020-09-07 16:36 ` [RFC 3/5] mm, page_alloc(): remove setup_pageset() Vlastimil Babka
2020-09-10 9:23 ` Oscar Salvador
2020-09-10 9:57 ` Oscar Salvador
2020-09-18 9:37 ` Vlastimil Babka
2020-09-10 11:00 ` David Hildenbrand
2020-09-07 16:36 ` [RFC 4/5] mm, page_alloc: cache pageset high and batch in struct zone Vlastimil Babka
2020-09-10 11:30 ` Oscar Salvador
2020-09-18 12:02 ` Vlastimil Babka
2020-09-07 16:36 ` [RFC 5/5] mm, page_alloc: disable pcplists during page isolation Vlastimil Babka
2020-09-09 10:48 ` Vlastimil Babka
2020-09-09 11:36 ` Michal Hocko
2020-09-09 11:44 ` David Hildenbrand
2020-09-09 12:57 ` David Hildenbrand
2020-09-09 11:55 ` Vlastimil Babka
2020-09-10 10:29 ` David Hildenbrand
2020-09-10 11:05 ` Vlastimil Babka
2020-09-10 12:42 ` David Hildenbrand
2020-09-09 12:53 ` Pavel Tatashin
2020-09-08 18:29 ` [RFC 0/5] " David Hildenbrand
2020-09-09 10:54 ` Vlastimil Babka
2020-09-09 11:27 ` osalvador
2020-09-09 11:29 ` David Hildenbrand [this message]
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