linux-kernel - Re: [PATCH 6/8] perf: Account freq events per cpu

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: <20130801142109.GH431@somewhere>
Date:	Thu, 1 Aug 2013 16:21:11 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 6/8] perf: Account freq events per cpu

On Thu, Aug 01, 2013 at 04:06:15PM +0200, Peter Zijlstra wrote:
> On Thu, Aug 01, 2013 at 04:03:52PM +0200, Peter Zijlstra wrote:
> > On Thu, Aug 01, 2013 at 03:55:27PM +0200, Frederic Weisbecker wrote:
> > > On Thu, Aug 01, 2013 at 03:31:55PM +0200, Peter Zijlstra wrote:
> > > > 
> > > > Where the freq thing is new and shiney, but we already had the other
> > > > two. Of those, cgroup events must be per cpu so that should be good,
> > > > the branch_stack thing tests ATTACH_TASK, which should also be good, but
> > > > leaves me wonder wth they do for those that are attached to tasks.
> > > > 
> > > > But yes, the frequency thing is borken.
> > > 
> > > Aie, so the freq thing,  I can either account to all CPUs (inc to all
> > > and send an IPI to all), or when the event scheds in/out. Probably we
> > > should do the former to avoid sending an IPI at all context switches.
> > 
> > Yeah, just go with a single global state for now..
> 
> The perf default is to create inherited counter, which are per cpu
> anyway. So we'll not loose much.

So you mean that I keep the per cpu state when event->cpu != -1 and also have
a global counter for the others. Right?
--
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/