From: Luiz Capitulino <lcapitulino@redhat.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
mtosatti@redhat.com, Mel Gorman <mgorman@suse.de>,
Andrea Arcangeli <aarcange@redhat.com>,
Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 0/4] hugetlb: add hugepagesnid= command-line option
Date: Tue, 11 Feb 2014 10:36:24 -0500 [thread overview]
Message-ID: <20140211103624.7edf1423@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1402101851190.3447@chino.kir.corp.google.com>
On Mon, 10 Feb 2014 18:54:20 -0800 (PST)
David Rientjes <rientjes@google.com> wrote:
> On Mon, 10 Feb 2014, Luiz Capitulino wrote:
>
> > HugeTLB command-line option hugepages= allows the user to specify how many
> > huge pages should be allocated at boot. On NUMA systems, this argument
> > automatically distributes huge pages allocation among nodes, which can
> > be undesirable.
> >
>
> And when hugepages can no longer be allocated on a node because it is too
> small, the remaining hugepages are distributed over nodes with memory
> available, correct?
No. hugepagesnid= tries to obey what was specified by the uses as much as
possible. So, if you specify that 10 1G huge pages should be allocated from
node0 but only 7 1G pages can actually be allocated, then hugepagesnid= will
do just that.
> > The hugepagesnid= option introduced by this commit allows the user
> > to specify which NUMA nodes should be used to allocate boot-time HugeTLB
> > pages. For example, hugepagesnid=0,2,2G will allocate two 2G huge pages
> > from node 0 only. More details on patch 3/4 and patch 4/4.
> >
>
> Strange, it would seem better to just reserve as many hugepages as you
> want so that you get the desired number on each node and then free the
> ones you don't need at runtime.
You mean, for example, if I have a 2 node system and want 2 1G huge pages
from node 1, then I have to allocate 4 1G huge pages and then free 2 pages
on node 0 after boot? That seems very cumbersome to me. Besides, what if
node0 needs this memory during boot?
> That probably doesn't work because we can't free very large hugepages that
> are reserved at boot, would fixing that issue reduce the need for this
> patchset?
I don't think so.
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next prev parent reply other threads:[~2014-02-11 18:58 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-10 17:27 [PATCH 0/4] hugetlb: add hugepagesnid= command-line option Luiz Capitulino
2014-02-10 17:27 ` [PATCH 1/4] memblock: memblock_virt_alloc_internal(): alloc from specified node only Luiz Capitulino
2014-02-10 23:27 ` Andrew Morton
2014-02-11 9:20 ` Mel Gorman
2014-02-10 17:27 ` [PATCH 2/4] memblock: add memblock_virt_alloc_nid_nopanic() Luiz Capitulino
2014-02-10 17:27 ` [PATCH 3/4] hugetlb: add hugepagesnid= command-line option Luiz Capitulino
2014-02-10 23:27 ` Andrew Morton
2014-02-11 15:26 ` Luiz Capitulino
2014-02-12 3:44 ` Yasuaki Ishimatsu
2014-02-12 19:39 ` Luiz Capitulino
2014-02-10 17:27 ` [PATCH 4/4] hugetlb: hugepagesnid=: add 1G huge page support Luiz Capitulino
2014-02-10 23:30 ` Andrew Morton
2014-02-11 15:27 ` Luiz Capitulino
2014-02-10 17:55 ` [PATCH 0/4] hugetlb: add hugepagesnid= command-line option Luiz Capitulino
2014-02-10 23:13 ` Andrew Morton
2014-02-11 3:58 ` Davidlohr Bueso
2014-02-11 15:10 ` Luiz Capitulino
2014-02-11 2:54 ` David Rientjes
2014-02-11 9:25 ` Mel Gorman
2014-02-11 15:26 ` Marcelo Tosatti
2014-02-11 17:10 ` Mel Gorman
2014-02-11 20:15 ` Marcelo Tosatti
2014-02-12 10:39 ` Mel Gorman
2014-02-11 15:36 ` Luiz Capitulino [this message]
2014-02-12 3:59 ` David Rientjes
2014-02-12 20:09 ` Luiz Capitulino
2014-02-11 21:17 ` Andi Kleen
2014-02-11 21:31 ` Luiz Capitulino
2014-02-12 2:37 ` Andi Kleen
2014-02-12 4:01 ` David Rientjes
2014-02-12 19:33 ` Luiz Capitulino
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