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Date: Fri, 18 Aug 2017 09:45:06 -0700
From: Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk
Message-ID: <20170818164506.GO28715@tassilo.jf.intel.com>
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To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>, "Liang, Kan" <kan.liang@intel.com>, Linus Torvalds <torvalds@linux-foundation.org>, Mel Gorman <mgorman@suse.de>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>

> Still, I don't think this problem is THP specific.  If there is a hot
> regular page getting migrated, we'll also see many threads get
> queued up quickly.  THP may have made the problem worse as migrating
> it takes a longer time, meaning more threads could get queued up.

Also THP probably makes more threads collide because the pages are larger.
But still it can all happen even without THP.

-Andi

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