From: Thomas Gleixner <tglx@linutronix.de>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Linux PM <linux-pm@vger.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
"David S. Miller" <davem@davemloft.net>,
Andrew Morton <akpm@linux-foundation.org>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH v4 2/2] powercap/rapl: reduce ipi calls
Date: Fri, 19 Feb 2016 23:01:59 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1602192301250.2477@nanos> (raw)
In-Reply-To: <alpine.DEB.2.11.1602192246070.2477@nanos>
On Fri, 19 Feb 2016, Thomas Gleixner wrote:
> On Fri, 19 Feb 2016, Jacob Pan wrote:
> > @@ -1380,6 +1375,7 @@ static int rapl_detect_topology(void)
> > int i;
> > int phy_package_id;
> > struct rapl_package *new_package, *rp;
> > + int lead_cpu;
> >
> > for_each_online_cpu(i) {
> > phy_package_id = topology_physical_package_id(i);
> > @@ -1392,7 +1388,11 @@ static int rapl_detect_topology(void)
> > /* add the new package to the list */
> > new_package->id = phy_package_id;
> > new_package->nr_cpus = 1;
> > -
> > + /* find the first active cpu of the package */
> > + lead_cpu = cpumask_any_and(topology_core_cpumask(i),
> > + cpumask_of(i));
>
> Yuck. Why any_and? The result is i, simply because i is online otherwise you
> would not be there.
>
> > + if (lead_cpu < nr_cpu_ids)
> > + new_package->lead_cpu = lead_cpu;
>
> So the above is identical to
>
> new_package->lead_cpu = lead_cpu;
new_package->lead_cpu = i;
Copy and paste sucks :)
> Hmm?
>
> > @@ -1500,6 +1503,15 @@ static int rapl_cpu_callback(struct notifier_block *nfb,
> > break;
> > if (--rp->nr_cpus == 0)
> > rapl_remove_package(rp);
> > + else if (cpu == rp->lead_cpu) {
> > + /* choose another active cpu in the package */
> > + lead_cpu = cpumask_any_but(topology_core_cpumask(cpu), cpu);
>
> This part is correct.
>
> Thanks,
>
> tglx
>
next prev parent reply other threads:[~2016-02-19 22:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 20:37 [PATCH v4 0/2] powercap/rapl: reduce ipi calls and misc clean up Jacob Pan
2016-02-19 20:37 ` [PATCH v4 1/2] cpumask: export cpumask_any_but Jacob Pan
2016-02-19 20:37 ` [PATCH v4 2/2] powercap/rapl: reduce ipi calls Jacob Pan
2016-02-19 21:50 ` Thomas Gleixner
2016-02-19 22:01 ` Thomas Gleixner [this message]
2016-02-19 22:23 ` Jacob Pan
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