linux-kernel - Re: conflict between tickless and perfmon2

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: <20071109201711.GA20390@frankl.hpl.hp.com>
Date:	Fri, 9 Nov 2007 12:17:11 -0800
From:	Stephane Eranian <eranian@....hp.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	perfmon2-devel@...ts.sourceforge.net, perfmon@...ali.hpl.hp.com,
	linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: conflict between tickless and perfmon2

Thomas,

On Fri, Nov 09, 2007 at 07:40:31PM +0100, Thomas Gleixner wrote:
> 
> > > It looks like a solution would be to change the implementation of
> > > timeout-based switching to use HR timers instead. Similar to what is
> > > done for ITIMER_REAL and ITIMER_VIRTUAL.
> 
> Using a hrtimer is perfrectly fine, I'd say it's preferred over hooks in 
> some code which has absoluty no guarantee of being executed periodically 
> or even executed at all. OTOH it seems rather stupid to measure stuff 
> while the system is idle and doing nothing.
> 
I'll start looking into this soon. To answer your point about idle,
this is not because the core is idle that counters do not capture events
related to buses or caches for instance.

-- 
-Stephane
-
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/