linux-kernel - Re: [PATCH] prctl: return MCE process flags through pointer

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] [day] [month] [year] [list]

Message-ID: <20091225093504.0c1224a2@infradead.org>
Date:	Fri, 25 Dec 2009 09:35:04 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Smith, GeoffX" <geoffx.smith@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Michael Stone <michael@...top.org>
Subject: Re: [PATCH] prctl: return MCE process flags through pointer

On Wed, 23 Dec 2009 10:54:50 -0800
Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Wed, 23 Dec 2009 09:56:04 -0800 "Smith, GeoffX"
> <geoffx.smith@...el.com> wrote:
> 
> > >Why are task_struct.timer_slack_ns and
> > >task_struct.default_timer_slack_ns unsigned long, btw?  AFACIT we
> > >could make them unsigned ints.
> > 
> > Timer slack is not a Boolean or enum, and we want the greatest
> > range possible.  (Actually, I'd like to talk Arjan into using the
> > same time structure as select(), but that's another discussion.)
> > Internally hrtimer uses unsigned long.  I know long and unsigned
> > long are the same on some architectures, but let's not introduce an
> > unnatural restriction -- recall that arg2 is unsigned long.
> 
> Using unsigned ints will reduce the size of the task_struct.
> 
> Is there any conceivable case for a timer_slack which exceeds four
> seconds?  

the largest I've seen asked in practice is 2 seconds.
But even at 100 msec or more you're talking about very special
applications; rounding up timers otherwise really impacts the
functionality of the app in a bad way.


> If so, what is it, and if so, why this:
> 
> #define MAX_SLACK       (100 * NSEC_PER_MSEC)

this is the max for "automatic slack"

-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
--
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/