linux-kernel - Re: [patch 54/55] timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC[

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:	Mon, 14 Jul 2014 12:39:26 +0000 (UTC)
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [patch 54/55] timekeeping: Provide fast and NMI safe access to
 CLOCK_MONOTONIC[_RAW]

----- Original Message -----
> From: "Peter Zijlstra" <peterz@...radead.org>
> To: "Thomas Gleixner" <tglx@...utronix.de>
> Cc: "LKML" <linux-kernel@...r.kernel.org>, "John Stultz" <john.stultz@...aro.org>, "Steven Rostedt"
> <rostedt@...dmis.org>, "Mathieu Desnoyers" <mathieu.desnoyers@...icios.com>
> Sent: Monday, July 14, 2014 5:47:50 AM
> Subject: Re: [patch 54/55] timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC[_RAW]
> 
> On Fri, Jul 11, 2014 at 01:45:19PM -0000, Thomas Gleixner wrote:
> > +static struct tk_fast tk_fast_raw  ____cacheline_aligned;
> > +static struct tk_fast tk_fast_mono ____cacheline_aligned;
> 
> Question to the 'trace maniacs'; why do you lot need access to mono_raw?
> 
> I would much prefer to limit choice here.

For LTTng, which I guess qualifies as bring part of the aforementioned
trace maniacs group, we only need the "tk_fast_mono" clock. We don't
need mono_raw.

We can then correlate with user-space traces by using tk_fast_mono in
kernel-space and using CLOCK_MONOTONIC in userspace.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
--
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/