linux-kernel - Re: [PATCH 09/15] x86, amd: add accessor for number of cores per compute unit

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: <20150831083821.GE16853@twins.programming.kicks-ass.net>
Date:	Mon, 31 Aug 2015 10:38:21 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Ingo Molnar <mingo@...nel.org>, Huang Rui <ray.huang@....com>,
	Borislav Petkov <bp@...e.de>, Jean Delvare <jdelvare@...e.de>,
	Guenter Roeck <linux@...ck-us.net>,
	Andy Lutomirski <luto@...capital.net>,
	Andreas Herrmann <herrmann.der.user@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	John Stultz <john.stultz@...aro.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	lm-sensors@...sensors.org, linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Andreas Herrmann <herrmann.der.user@...glemail.com>,
	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, Tony Li <tony.li@....com>
Subject: Re: [PATCH 09/15] x86, amd: add accessor for number of cores per
 compute unit

On Sun, Aug 30, 2015 at 05:53:22PM +0200, Borislav Petkov wrote:
> On Sat, Aug 29, 2015 at 11:19:14AM +0200, Ingo Molnar wrote:
> > So let me withdraw my ack: the much more important question that I
> > missed first time around, why is this reporting feature living in
> > hwmon, not in perf? We have energy reporting facilities in perf that
> > this should be synced to.
> 
> Because there's already fam15h_power driver which is exactly for that.
> Making it part of perf is then a question of cat-ting the same sysfs
> file twice, at the beginning and at the end of the trace, which is
> trivial.

That don't make sense.

Looking at the BKDG Fam 15h 60h-6Fh these MSRs are per compute unit.
This means you can do much finer grained measurements than system wide
-- which is all hwmon seems capable of.

Not to mention the proposed code is horrible, who in their right mind
does two rdmsrl_safe_on_cpu() back to back.


--
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/