Re: [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even when deferred

From: Kirill A. Shutemov
Date: Thu Dec 22 2016 - 03:31:35 EST


On Wed, Dec 21, 2016 at 04:21:54PM -0800, David Rientjes wrote:
> Currently, when defrag is set to "madvise", thp allocations will direct
> reclaim. However, when defrag is set to "defer", all thp allocations do
> not attempt reclaim regardless of MADV_HUGEPAGE.
>
> This patch always directly reclaims for MADV_HUGEPAGE regions when defrag
> is not set to "never." The idea is that MADV_HUGEPAGE regions really
> want to be backed by hugepages and are willing to endure the latency at
> fault as it was the default behavior prior to commit 444eb2a449ef ("mm:
> thp: set THP defrag by default to madvise and add a stall-free defrag
> option").
>
> In this form, "defer" is a stronger, more heavyweight version of
> "madvise".
>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>

Makes senses to me.

Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>

--
Kirill A. Shutemov