linux-kernel - Re: [PATCH 2/5] perf, x86: Enable PDIR precise instruction profiling on IvyBridge

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:	Tue, 3 Jul 2012 01:13:22 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 2/5] perf, x86: Enable PDIR precise instruction profiling
 on IvyBridge

On Mon, Jul 2, 2012 at 11:57 PM, Andi Kleen <ak@...ux.intel.com> wrote:
> On Mon, Jul 02, 2012 at 11:36:54PM +0200, Peter Zijlstra wrote:
>> On Mon, 2012-07-02 at 14:00 -0700, Andi Kleen wrote:
>> > Ok so you want a new flag? Or a new event?
>>
>> Once we grow the sysfs event stuff for cpu PMUs, we could add a new
>> named event, but I don't think its all that important.
>>
>> instructions isn't all that interesting a measure to sample. And the
>> people that do care can already use it by filling out the event
>> manually.
>
> The idea was to make it easier to use, similar to the recent
> automatic IBS setup on AMD.
>
> It's the nearest you can get on Intel systems.
>
> I agree it would be nicer on cycles, but instructions are in many
> cases a reasonable approximation.
>
> BTW the problem with specifying it manually is that there
> is no way to enforce the SandyBridge quiescence restrictions.

Well, the only way I can think of would be to request that the
event be programmed with exclusive mode ALWAYS. That
should not be to hard to add.

> It would probably need forking the tables too and removing it on
> SandyBridge, or something special to enforce exclusive mode,
> all complicated and ugly.
>
> An explicit way to specify it side steps that all nicely.
>
> -Andi
>
> --
> ak@...ux.intel.com -- Speaking for myself only
--
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/