linux-kernel - Re: [RFC 00/11] THP swap: Delay splitting THP during swapping out

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87k2fp4zxt.fsf@yhuang-mobile.sh.intel.com>
Date:	Tue, 09 Aug 2016 10:25:34 -0700
From:	"Huang\, Ying" <ying.huang@...el.com>
To:	Andrew Morton <akpm@...ux-foundation.org>, <tim.c.chen@...el.com>,
	<dave.hansen@...el.com>, <andi.kleen@...el.com>,
	<aaron.lu@...el.com>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>
Cc:	"Huang\, Ying" <ying.huang@...el.com>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [RFC 00/11] THP swap: Delay splitting THP during swapping out

Hi, All,

"Huang, Ying" <ying.huang@...el.com> writes:

> From: Huang Ying <ying.huang@...el.com>
>
> This patchset is based on 8/4 head of mmotm/master.
>
> This is the first step for Transparent Huge Page (THP) swap support.
> The plan is to delaying splitting THP step by step and avoid splitting
> THP finally during THP swapping out and swapping in.
>
> The advantages of THP swap support are:
>
> - Batch swap operations for THP to reduce lock acquiring/releasing,
>   including allocating/freeing swap space, adding/deleting to/from swap
>   cache, and writing/reading swap space, etc.
>
> - THP swap space read/write will be 2M sequence IO.  It is particularly
>   helpful for swap read, which usually are 4k random IO.
>
> - It will help memory fragmentation, especially when THP is heavily used
>   by the applications.  2M continuous pages will be free up after THP
>   swapping out.
>
> As the first step, in this patchset, the splitting huge page is
> delayed from almost the first step of swapping out to after allocating
> the swap space for THP and adding the THP into swap cache.  This will
> reduce lock acquiring/releasing for locks used for swap space and swap
> cache management.

For this patchset posting,

In general, I want to check the basic design with memory management
subsystem maintainers and developers.

For [RFC 01/11] swap: Add swap_cluster_list, it is a cleanup patch.  And
I think it should be useful independently.

I am not very confident about the memcg part, that is

[RFC 03/11] mm, memcg: Add swap_cgroup_iter iterator
[RFC 04/11] mm, memcg: Support to charge/uncharge multiple swap entries

Please help me to check it.

Best Regards,
Huang, Ying