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Date:   Wed, 27 Jun 2018 23:18:39 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Huang\, Ying" <ying.huang@intel.com>
Cc:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        Hugh Dickins <hughd@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one
 piece
Message-Id: <20180627231839.e5ac2f38e0397979d3db7765@linux-foundation.org>
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        <20180627215144.73e98b01099191da59bff28c@linux-foundation.org>
        <87r2krfpi2.fsf@yhuang-dev.intel.com>
        <20180627223118.dd2f52d87f53e7e002ed0153@linux-foundation.org>
        <87muvffp7w.fsf@yhuang-dev.intel.com>
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On Thu, 28 Jun 2018 13:35:15 +0800 "Huang\, Ying" <ying.huang@intel.com> wrote:

> Andrew Morton <akpm@linux-foundation.org> writes:
> 
> > On Thu, 28 Jun 2018 13:29:09 +0800 "Huang\, Ying" <ying.huang@intel.com> wrote:
> >
> >> Andrew Morton <akpm@linux-foundation.org> writes:
> >> 
> >> > On Fri, 22 Jun 2018 11:51:30 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
> >> >
> >> >> This is the final step of THP (Transparent Huge Page) swap
> >> >> optimization.  After the first and second step, the splitting huge
> >> >> page is delayed from almost the first step of swapout to after swapout
> >> >> has been finished.  In this step, we avoid splitting THP for swapout
> >> >> and swapout/swapin the THP in one piece.
> >> >
> >> > It's a tremendously good performance improvement.  It's also a
> >> > tremendously large patchset :(
> >> >
> >> > And it depends upon your
> >> > mm-swap-fix-race-between-swapoff-and-some-swap-operations.patch and
> >> > mm-fix-race-between-swapoff-and-mincore.patch, the first of which has
> >> > been floating about since February without adequate review.
> >> >
> >> > I'll give this patchset a spin in -mm to see what happens and will come
> >> > back later to take a closer look.  But the best I can do at this time
> >> > is to hopefully cc some possible reviewers :)
> >> 
> >> Thanks a lot for your help!  Hope more people can review it!
> >
> > I took it out of -mm again, temporarily.  Due to a huge tangle with the
> > xarray conversions in linux-next.
> 
> No problem.  I will rebase the patchset on your latest -mm tree, or the
> next version to be released?

We need to figure that out with Matthew.

Probably the xarray conversions are simpler and more mature so yes,
probably they should be staged first.