From: Michal Hocko <mhocko@suse.cz>
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Hillf Danton <dhillf@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] mm/hugetlb: gigantic hugetlb page pools shrink supporting
Date: Thu, 4 Apr 2013 18:20:23 +0200 [thread overview]
Message-ID: <20130404162023.GQ29911@dhcp22.suse.cz> (raw)
In-Reply-To: <20130404161746.GP29911@dhcp22.suse.cz>
On Thu 04-04-13 18:17:46, Michal Hocko wrote:
> On Thu 04-04-13 17:09:08, Wanpeng Li wrote:
> > order >= MAX_ORDER pages are only allocated at boot stage using the
> > bootmem allocator with the "hugepages=xxx" option. These pages are never
> > free after boot by default since it would be a one-way street(>= MAX_ORDER
> > pages cannot be allocated later), but if administrator confirm not to
> > use these gigantic pages any more, these pinned pages will waste memory
> > since other users can't grab free pages from gigantic hugetlb pool even
> > if OOM, it's not flexible. The patchset add hugetlb gigantic page pools
> > shrink supporting. Administrator can enable knob exported in sysctl to
> > permit to shrink gigantic hugetlb pool.
>
> I am not sure I see why the new knob is needed.
> /sys/kernel/mm/hugepages/hugepages-*/nr_hugepages is root interface so
> an additional step to allow writing to the file doesn't make much sense
> to me to be honest.
>
> Support for shrinking gigantic huge pages makes some sense to me but I
> would be interested in the real world example. GB pages are usually used
> in very specific environments where the amount is usually well known.
>
> I could imagine nr_hugepages_mempolicy would make more sense to free
> pages from particular nodes so they could be offlined for example.
> Does the patchset handles this as well?
Ohh, I should have checked before asking. Both knobs use the same
hugetlb_sysctl_handler_common and unless there is something hardcoded in
the patches then it should be supproted.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2013-04-04 16:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 9:09 Wanpeng Li
2013-04-04 9:09 ` [PATCH 1/6] mm/hugetlb: introduce new sysctl knob which control gigantic page pools shrinking Wanpeng Li
2013-04-04 9:09 ` [PATCH 2/6] mm/hugetlb: update_and_free_page gigantic pages awareness Wanpeng Li
2013-04-04 9:09 ` [PATCH 3/6] mm/hugetlb: enable gigantic hugetlb page pools shrinking Wanpeng Li
2013-04-04 9:09 ` [PATCH 4/6] mm/hugetlb: use already exist huge_page_order() instead of h->order Wanpeng Li
2013-04-04 9:09 ` [PATCH 5/6] mm/hugetlb: remove redundant hugetlb_prefault Wanpeng Li
2013-04-04 9:09 ` [PATCH 6/6] mm/hugetlb: use already exist interface huge_page_shift Wanpeng Li
2013-04-04 16:17 ` [PATCH 0/6] mm/hugetlb: gigantic hugetlb page pools shrink supporting Michal Hocko
2013-04-04 16:20 ` Michal Hocko [this message]
2013-04-05 1:29 ` Wanpeng Li
2013-04-05 1:29 ` Wanpeng Li
2013-04-04 23:41 ` Wanpeng Li
2013-04-04 23:41 ` Wanpeng Li
2013-04-05 8:12 ` Michal Hocko
2013-04-05 8:27 ` Wanpeng Li
2013-04-05 8:27 ` Wanpeng Li
2013-04-05 9:27 ` Michal Hocko
2013-04-05 8:54 ` Simon Jeons
2013-04-05 9:52 ` Michal Hocko
2013-04-04 23:35 ` Wanpeng Li
2013-04-04 23:35 ` Wanpeng Li
2013-04-11 23:29 ` Wanpeng Li
2013-04-12 15:22 ` Andi Kleen
2013-07-15 11:31 ` Wanpeng Li
2013-07-15 11:31 ` Wanpeng Li
2014-08-21 23:37 ` Wanpeng Li
2014-08-22 1:34 ` Zhang Yanfei
2014-08-22 4:04 ` Wanpeng Li
2014-08-22 14:18 ` Andi Kleen
2013-04-11 23:29 ` Wanpeng Li
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