linux-kernel - Re: [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one piece

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Date:   Wed, 4 Jul 2018 11:11:53 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     "Huang, Ying" <ying.huang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Hugh Dickins <hughd@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>
Subject: Re: [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one
 piece

On (06/27/18 21:51), Andrew Morton wrote:
> On Fri, 22 Jun 2018 11:51:30 +0800 "Huang, Ying" <ying.huang@...el.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 :(

Will zswap gain a THP swap out/in support at some point?


mm/zswap.c: static int zswap_frontswap_store(...)
...
	/* THP isn't supported */
	if (PageTransHuge(page)) {
		ret = -EINVAL;
		goto reject;
	}

	-ss