Messages in this thread | | | Date | Wed, 17 Feb 2016 10:27:11 -0800 (PST) | From | Vikas Shivappa <> | Subject | Re: [PATCH] x86/perf/intel/cqm: Get rid of the silly for_each_cpu lookups |
| |
On Wed, 17 Feb 2016, Thomas Gleixner wrote:
> On Wed, 17 Feb 2016, Thomas Gleixner wrote: > >> CQM is a strict per package facility. Use the proper cpumasks to lookup the >> readers. > > Sorry for the noise. PEBKAC: quilt refresh missing. Correct version below. > > Thanks, > > tglx > > 8<---------- > > Subject: x86/perf/cqm: Get rid of the silly for_each_cpu lookups > From: Thomas Gleixner <tglx@linutronix.de> > Date: Sun, 14 Feb 2016 23:09:06 +0100 > > CQM is a strict per package facility. Use the proper cpumasks to lookup the > readers. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > arch/x86/kernel/cpu/perf_event_intel_cqm.c | 34 ++++++++++------------------- > 1 file changed, 12 insertions(+), 22 deletions(-) > > --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c > @@ -1244,15 +1244,12 @@ static struct pmu intel_cqm_pmu = { > > static inline void cqm_pick_event_reader(int cpu) > { > - int phys_id = topology_physical_package_id(cpu); > - int i; > + int reader; > > - for_each_cpu(i, &cqm_cpumask) { > - if (phys_id == topology_physical_package_id(i)) > - return; /* already got reader for this socket */ > - } > - > - cpumask_set_cpu(cpu, &cqm_cpumask); > + /* First online cpu in package becomes the reader */ > + reader = cpumask_any_and(topology_core_cpumask(cpu), &cqm_cpumask); > + if (reader >= nr_cpu_ids) > + cpumask_set_cpu(cpu, &cqm_cpumask);
I was confused by the topology_core_cpumask naming as its really the mask of all cpus in the same package. I sent a patch for cqm and rapl to fix this looping when you had given the same feedback during CAt patches review , but they have never made it so far due to CAT patch issues.
Would it be better to resend the rapl (looks like perf_uncore has same loop) fixes separately ?
Thanks, Vikas
> } > > static void intel_cqm_cpu_starting(unsigned int cpu) > @@ -1270,24 +1267,17 @@ static void intel_cqm_cpu_starting(unsig > > static void intel_cqm_cpu_exit(unsigned int cpu) > { > - int phys_id = topology_physical_package_id(cpu); > - int i; > + int target; > > - /* > - * Is @cpu a designated cqm reader? > - */ > + /* Is @cpu the current cqm reader for this package ? */ > if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask)) > return; > > - for_each_online_cpu(i) { > - if (i == cpu) > - continue; > - > - if (phys_id == topology_physical_package_id(i)) { > - cpumask_set_cpu(i, &cqm_cpumask); > - break; > - } > - } > + /* Find another online reader in this package */ > + target = cpumask_any_but(topology_core_cpumask(cpu), cpu); > + > + if (target < nr_cpu_ids) > + cpumask_set_cpu(target, &cqm_cpumask); > } > > static int intel_cqm_cpu_notifier(struct notifier_block *nb, > >
| |