linux-kernel - Re: [PATCH 01/10] mm: allow swappiness that prefers anon over file

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: <20160609133205.GA11719@cmpxchg.org>
Date:	Thu, 9 Jun 2016 09:32:05 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Minchan Kim <minchan@...nel.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Michal Hocko <mhocko@...e.cz>,
	Tim Chen <tim.c.chen@...ux.intel.com>, kernel-team@...com
Subject: Re: [PATCH 01/10] mm: allow swappiness that prefers anon over file

On Thu, Jun 09, 2016 at 10:01:07AM +0900, Minchan Kim wrote:
> A system has big HDD storage and SSD swap.
> 
> HDD:    200 IOPS
> SSD: 100000 IOPS
> From https://en.wikipedia.org/wiki/IOPS
> 
> So, speed gap is 500x.
> x + 500x = 200
> If we use PCIe-SSD, the gap will be larger.
> That's why I said 200 is enough to represent speed gap.

Ah, I see what you're saying.

Yeah, that's unfortunately a limitation in the current ABI. Extending
the range to previously unavailable settings is doable; changing the
meaning of existing values is not. We'd have to add another interface.

> Such system configuration is already non-sense so it is okay to ignore such
> usecases?

I'm not sure we have to be proactive about it, but we can always add a
more fine-grained knob to override swappiness when somebody wants to
use such a setup in practice.