From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH v3] powercap/rapl: reduce ipi calls
Date: Wed, 17 Feb 2016 10:04:04 -0800 [thread overview]
Message-ID: <20160217100404.5a59649a@icelake> (raw)
In-Reply-To: <alpine.DEB.2.11.1602171652010.19512@nanos>
On Wed, 17 Feb 2016 17:04:41 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:
> > >
> > > for_each_online_cpu(i) {
> > > if (topology_physical_package_id(i) ==
> > > package_id)
>
> This is still crap. We really want a proper handling for that which
> does not require these silly for_each_cpu() loops.
>
> That code already has a hotplug notifier, so you can track one online
> cpu in the package like we do in cqm and other facilities.
>
> The first online cpu of a package sets itself as 'owner'. On unplug
> it looks up:
>
> rpl->cpu = cpumask_any_but(topology_core_cpumask(cpu), cpu);
>
> So if this is the last cpu then rpl->cpu becomes nr_cpu_ids.
>
> So that whole nonsense can be avoided completely.
ok, that would work nicely, similar to cqm_pick_event_reader().
thanks for the tip. just fyi, unlike perf cqm, rapl runtime change is
expected to be low frequency.
next prev parent reply other threads:[~2016-02-17 18:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 19:04 [PATCH v3] powercap/rapl: reduce ipi calls Jacob Pan
2016-02-16 0:54 ` Rafael J. Wysocki
2016-02-17 16:04 ` Thomas Gleixner
2016-02-17 18:04 ` Jacob Pan [this message]
2016-02-17 18:22 ` Thomas Gleixner
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