From: Michal Hocko <mhocko@suse.com>
To: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
mike.kravetz@Oracle.com, n-horiguchi@ah.jp.nec.com,
aneesh.kumar@linux.vnet.ibm.com, gerald.schaefer@de.ibm.com,
zhongjiang@huawei.com, aarcange@redhat.com,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH] mm/hugetlb: Warn the user when issues arise on boot due to hugepages
Date: Wed, 14 Jun 2017 09:25:36 +0200 [thread overview]
Message-ID: <20170614072536.GG6045@dhcp22.suse.cz> (raw)
In-Reply-To: <20170613152501.w27r2q2agy4sue5x@oracle.com>
On Tue 13-06-17 11:25:02, Liam R. Howlett wrote:
> * Michal Hocko <mhocko@suse.com> [170613 01:42]:
> > On Mon 12-06-17 21:35:17, Liam R. Howlett wrote:
> > [...]
> > > Understood. Again, I appreciate all the time you have taken on my
> > > patch and explaining your points. I will look at this again as you
> > > have suggested.
> >
> > One way to go forward might be to check the size of the per node pool
> > and warn if it grows over a certain threshold of the available memory
> > on that node. I do not have a good idea what would be that threshold,
> > though. It will certainly depend on workloads. I can also imagine that
> > somebody might want to dedicate the full numa node for hugetlb pages
> > and still be OK so take this suggestion with some reserve. It is hard
> > to protect against misconfigurations in general but maybe you will find
> > some way here.
>
> I thought about an upper threshold of memory and discussed it
> internally, but came to the same conclusion; it may be desired and
> there's no safe bet beyond warning if the user requests over 100% of the
> memory. In the case of requesting over 100% of the memory, we could
> warn the user and specify what was allocated. Would it be reasonable to
> warn on both boot and through sysfs of such requests? I'm concerned
> that this is yet another too-targeted approach.
No, I think 100% is just too targeted. As I've said already said, a good
enough treshold might be hard to get right but filling up more than 90%
of memory with hugetlb pages will just bite you unless you know what you
are doing. And if so you can safely ignore such a warning...
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-06-14 7:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-03 0:54 [PATCH] mm/hugetlb: Warn the user when issues arise on boot due to hugepages Liam R. Howlett
2017-06-05 4:57 ` Michal Hocko
2017-06-05 15:15 ` Liam R. Howlett
2017-06-06 5:49 ` Michal Hocko
2017-06-06 6:01 ` Michal Hocko
2017-06-12 17:28 ` Liam R. Howlett
2017-06-12 17:49 ` Michal Hocko
2017-06-12 18:37 ` Liam R. Howlett
2017-06-12 18:52 ` Michal Hocko
2017-06-13 1:35 ` Liam R. Howlett
2017-06-13 5:42 ` Michal Hocko
2017-06-13 15:25 ` Liam R. Howlett
2017-06-13 16:26 ` Mike Kravetz
2017-06-14 7:27 ` Michal Hocko
2017-06-14 17:02 ` Mike Kravetz
2017-06-14 7:25 ` Michal Hocko [this message]
2017-06-16 19:07 ` Andrew Morton
2017-06-17 0:25 ` Mike Kravetz
2017-06-17 6:51 ` Michal Hocko
2017-06-19 19:59 ` Liam R. Howlett
2017-06-05 22:38 ` Andrew Morton
2017-06-06 19:03 ` Matthew Wilcox
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