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Date: Wed, 28 Dec 2016 13:33:49 -0800 (PST)
From: David Rientjes <rientjes@google.com>
Subject: Re: [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even
 when deferred
In-Reply-To: <20161228084823.GB11470@dhcp22.suse.cz>
Message-ID: <alpine.DEB.2.10.1612281332320.13632@chino.kir.corp.google.com>
References: <20161222100009.GA6055@dhcp22.suse.cz> <alpine.DEB.2.10.1612221259100.29036@chino.kir.corp.google.com> <20161223085150.GA23109@dhcp22.suse.cz> <alpine.DEB.2.10.1612230154450.88514@chino.kir.corp.google.com> <20161223111817.GC23109@dhcp22.suse.cz>
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Sender: owner-linux-mm@kvack.org
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To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jonathan Corbet <corbet@lwn.net>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@techsingularity.net>, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On Wed, 28 Dec 2016, Michal Hocko wrote:

> I do care more about _users_ and their _experience_ than what
> application _writers_ think is the best. This is the whole point
> of giving the defrag tunable. madvise(MADV_HUGEPAGE) is just a hint to
> the system that using transparent hugepages is _preferable_, not
> mandatory. We have an option to allow stalls for those vmas to increase
> the allocation success rate. We also have tunable to completely ignore
> it. And we should also have an option to not stall.
> 

The application developer who uses madvise(MADV_HUGEPAGE) is doing so for 
a reason.

We lack the ability to defragment in the background for all users who 
don't want to block while allowing madvise(MADV_HUGEPAGE) users to block, 
as the changelog for this patch clearly indicates.

Thanks.

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