linux-kernel - RE: [PATCH -v2 -mm] add extra free kbytes tunable

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: <65795E11DBF1E645A09CEC7EAEE94B9CB516CBC4@USINDEVS02.corp.hds.com>
Date:	Tue, 11 Oct 2011 15:32:11 -0400
From:	Satoru Moriya <satoru.moriya@....com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>
CC:	Rik van Riel <riel@...hat.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	Satoru Moriya <smoriya@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"lwoodman@...hat.com" <lwoodman@...hat.com>,
	Seiji Aguchi <saguchi@...hat.com>,
	"hughd@...gle.com" <hughd@...gle.com>,
	"hannes@...xchg.org" <hannes@...xchg.org>
Subject: RE: [PATCH -v2 -mm] add extra free kbytes tunable

On 10/10/2011 06:37 PM, Andrew Morton wrote:
> On Fri, 7 Oct 2011 20:08:19 -0700 (PDT) David Rientjes 
> <rientjes@...gle.com> wrote:
> 
>> On Thu, 1 Sep 2011, Rik van Riel wrote:
>
> The page allocator already tries harder if the caller has 
> rt_task(current).  Why is this inadequate?  Can we extend this idea 
> further to fix whatever-the-problem-is?

Actually page allocator decreases min watermark to 3/4 * min watermark
for rt-task. But in our case some applications create a lot of
processes and if all of them are rt-task, the amount of watermark
bonus(1/4 * min watermark) is not enough.

If we can tune the amount of bonus, it may be fine. But that is
almost all same as extra free kbytes.

> Does there exist anything like a test case which demonstrates the need 
> for this feature?

Unfortunately I don't have a real test case but just simple one.
And in my simple test case, I can avoid direct reclaim if we set
workload as rt-task.

The simple test case I used is following:
http://marc.info/?l=linux-mm&m=131605773321672&w=2

Regards,
Satoru
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/