From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages
Date: Mon, 1 Mar 2021 13:57:59 +0100 [thread overview]
Message-ID: <20210301125754.GA4003@linux> (raw)
In-Reply-To: <ff780dd6-f473-5476-fc1c-9f9bbcdb17c8@redhat.com>
On Mon, Mar 01, 2021 at 01:43:00PM +0100, David Hildenbrand wrote:
> Same experiment with ZONE_MOVABLE:
>
> a) Free huge pages: all memory can get unplugged again.
>
> b) Allocated/populated but idle huge pages: all memory can get unplugged
> again.
>
> c) Allocated/populated but all 512 huge pages are read/written in a loop:
> all memory can get unplugged again, but I get a single
>
> [ 121.192345] alloc_contig_range: [180000, 188000) PFNs busy
>
> Most probably because it happened to try migrating a huge page while it was
> busy. As virtio-mem retries on ZONE_MOVABLE a couple of times, it can deal
> with this temporary failure.
>
>
>
> Last but not least, I did something extreme:
>
> ]# cat /proc/meminfo
> MemTotal: 5061568 kB
> MemFree: 186560 kB
> MemAvailable: 354524 kB
> ...
> HugePages_Total: 2048
> HugePages_Free: 2048
> HugePages_Rsvd: 0
> HugePages_Surp: 0
>
>
> Triggering unplug would require to dissolve+alloc - which now fails when
> trying to allocate an additional ~512 huge pages (1G).
>
>
> As expected, I can properly see memory unplug not fully succeeding. + I get
> a fairly continuous stream of
>
> [ 226.611584] alloc_contig_range: [19f400, 19f800) PFNs busy
> ...
>
> But more importantly, the hugepage count remains stable, as configured by
> the admin (me):
>
> HugePages_Total: 2048
> HugePages_Free: 2048
> HugePages_Rsvd: 0
> HugePages_Surp: 0
Thanks for giving it a spin David, that is highly appreciated ;-)!
I will add above information in next's version changelog if you do not mind,
so the before-and-after can be seen clearly.
I shall send v4 in the course of the next few days.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-03-01 12:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 13:51 [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 1/2] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-02-25 20:03 ` Mike Kravetz
2021-02-26 9:48 ` Oscar Salvador
2021-02-26 8:35 ` Michal Hocko
2021-02-26 8:38 ` Michal Hocko
2021-02-26 9:25 ` David Hildenbrand
2021-02-26 9:47 ` Oscar Salvador
2021-02-26 9:45 ` Oscar Salvador
2021-02-26 9:51 ` Michal Hocko
2021-03-01 14:09 ` David Hildenbrand
2021-03-04 10:19 ` Oscar Salvador
2021-03-04 10:32 ` David Hildenbrand
2021-03-04 10:41 ` Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-02-25 23:05 ` Mike Kravetz
2021-02-26 8:46 ` Michal Hocko
2021-02-26 10:24 ` Oscar Salvador
2021-02-26 10:27 ` Oscar Salvador
2021-02-26 12:46 ` Michal Hocko
2021-02-28 13:43 ` Oscar Salvador
2021-03-05 17:30 ` David Hildenbrand
2021-03-01 12:43 ` [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages David Hildenbrand
2021-03-01 12:57 ` Oscar Salvador [this message]
2021-03-01 12:59 ` David Hildenbrand
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