linux-kernel - Re: [PULL] hardware latency detector

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: <1245375140.14766.25.camel@localhost.localdomain>
Date:	Thu, 18 Jun 2009 21:32:20 -0400
From:	Jon Masters <jonathan@...masters.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Jon Masters <jcm@...masters.org>, mingo@...e.hu,
	tglx@...utronix.de, williams@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PULL] hardware latency detector

On Thu, 2009-06-18 at 18:25 -0700, Linus Torvalds wrote:
> 
> On Thu, 18 Jun 2009, Jon Masters wrote:
> > 
> > Please pull "hwlat", the hardware latency detector for 2.6.31.
> 
> I really want to know more before I pull.

Ok.

> Has this been in -next?

No, it hasn't. But it has been tested quite extensively by a number of
people and is currently in the -rt tree.

> Discussed on lkml?

Yes. I posted an RFC patch back when it was called the SMI detector,
then a patch last week with the new generic name of hardware latency
detector (at Ingo's suggestion of renaming).

> How does it work?

It started as an SMI detector. Basically, when this module is loaded and
enabled, it will grab all CPUs in periodic calls to stop_machine and sit
in a configurable loop, looking for unexplainable latencies. Doing it
this way allows us to look for something stealing the CPU from Linux
without the kernel knowing - we report the statistics via debugfs.

Hope that helps! Thanks Linus!

Jon.

--
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/