Messages in this thread Patch in this message | | | Date | Wed, 17 Feb 2016 17:08:57 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86/perf/intel/cqm: Get rid of the silly for_each_cpu lookups |
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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
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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); } 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,
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