linux-kernel - Re: [PATCH] process cputimer is moving faster than its corresponding clock

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]

Date:	Sun, 14 Apr 2013 21:55:09 -0400
From:	Olivier Langlois <olivier@...llion01.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...hat.com, tglx@...utronix.de, fweisbec@...il.com,
	schwidefsky@...ibm.com, rostedt@...dmis.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] process cputimer is moving faster than its
 corresponding clock

On Fri, 2013-04-12 at 11:16 +0200, Peter Zijlstra wrote:
> On Wed, 2013-04-10 at 11:48 -0400, Olivier Langlois wrote:
> > Please explain how expensive it is. All I am seeing is a couple of
> > additions.
> 
> Let me start with this, since your earlier argument also refers to
> this.
> 
> So yes it does look simple and straight fwd, only one addition. However
> its an atomic operation across all threads of the same process. Imagine
> a single process with 512 threads, all running on a separate cpu.
> 
Peter,

It now makes perfect sense. Thank you for your explanation. It is
showing me an aspect that I did overlook.

Greetings,


--
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/