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[tip:x86/cache] x86/intel_cqm: Modify hot cpu notification handling

From tip-bot for Fenghua Yu <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:x86/cache] x86/intel_cqm: Modify hot cpu notification handling
Date 2015-12-18 22:40 +0100
Message-ID <qHaUP-2Dm-47@gated-at.bofh.it> (permalink)
References <qGN2b-48Z-25@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  8a91dc4e92327b61fbe5941d25e74660e2a44579
Gitweb:     http://git.kernel.org/tip/8a91dc4e92327b61fbe5941d25e74660e2a44579
Author:     Fenghua Yu <fenghua.yu@intel.com>
AuthorDate: Thu, 17 Dec 2015 14:46:06 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Fri, 18 Dec 2015 13:17:55 -0800

x86/intel_cqm: Modify hot cpu notification handling

From: Vikas Shivappa <vikas.shivappa@linux.intel.com>

 - In cqm_pick_event_reader, use the existing package<->core map instead
 of looping through all cpus in cqm_cpumask.

 - In intel_cqm_cpu_exit, use the same map instead of looping through
 all online cpus. In large systems with large number of cpus the time
 taken to loop may be expensive and also the time increases linearly.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Link: http://lkml.kernel.org/r/1450392376-6397-2-git-send-email-fenghua.yu@intel.com
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
 arch/x86/kernel/cpu/perf_event_intel_cqm.c | 34 +++++++++++++++---------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
index a316ca9..dd82bc7 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
@@ -62,6 +62,12 @@ static LIST_HEAD(cache_groups);
  */
 static cpumask_t cqm_cpumask;
 
+/*
+ * Temporary cpumask used during hot cpu notificaiton handling. The usage
+ * is serialized by hot cpu locks.
+ */
+static cpumask_t tmp_cpumask;
+
 #define RMID_VAL_ERROR		(1ULL << 63)
 #define RMID_VAL_UNAVAIL	(1ULL << 62)
 
@@ -1244,15 +1250,13 @@ 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;
+	cpumask_and(&tmp_cpumask, &cqm_cpumask, topology_core_cpumask(cpu));
 
-	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);
+	/*
+	 * Pick a reader if there isn't one already.
+	 */
+	if (cpumask_empty(&tmp_cpumask))
+		cpumask_set_cpu(cpu, &cqm_cpumask);
 }
 
 static void intel_cqm_cpu_starting(unsigned int cpu)
@@ -1270,7 +1274,6 @@ static void intel_cqm_cpu_starting(unsigned int cpu)
 
 static void intel_cqm_cpu_exit(unsigned int cpu)
 {
-	int phys_id = topology_physical_package_id(cpu);
 	int i;
 
 	/*
@@ -1279,15 +1282,12 @@ static void intel_cqm_cpu_exit(unsigned int cpu)
 	if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask))
 		return;
 
-	for_each_online_cpu(i) {
-		if (i == cpu)
-			continue;
+	cpumask_and(&tmp_cpumask, topology_core_cpumask(cpu), cpu_online_mask);
+	cpumask_clear_cpu(cpu, &tmp_cpumask);
+	i = cpumask_any(&tmp_cpumask);
 
-		if (phys_id == topology_physical_package_id(i)) {
-			cpumask_set_cpu(i, &cqm_cpumask);
-			break;
-		}
-	}
+	if (i < nr_cpu_ids)
+		cpumask_set_cpu(i, &cqm_cpumask);
 }
 
 static int intel_cqm_cpu_notifier(struct notifier_block *nb,
--
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Thread

[PATCH V16 00/11] x86: Intel Cache Allocation Technology Support "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
  [PATCH V16 01/11] x86/intel_cqm: Modify hot cpu notification handling "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_cqm:   Modify hot cpu notification handling tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 03/11] x86/intel_rdt: Cache Allocation documentation "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt: Cache Allocation documentation tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 07/11] x86/intel_rdt: Implement scheduling support for Intel RDT "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt:   Implement scheduling support for Intel RDT tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 04/11] x86/intel_rdt: Add support for Cache Allocation detection "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt:   Add support for Cache Allocation detection tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 09/11] x86/intel_rdt: Intel haswell Cache Allocation enumeration "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt:   Intel haswell Cache Allocation enumeration tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 08/11] x86/intel_rdt: Hot cpu support for Cache Allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt:   Hot cpu support for Cache Allocation tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 06/11] x86/intel_rdt: Add L3 cache capacity bitmask management "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86/intel_rdt:   Add L3 cache capacity bitmask management tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
  [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface to manage Intel cache allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2015-12-17 21:10 +0100
    [tip:x86/cache] x86,cgroup/intel_rdt :   Add a cgroup interface to manage Intel cache allocation tip-bot for Fenghua Yu <tipbot@zytor.com> - 2015-12-18 22:40 +0100
    Re: [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface  to manage Intel cache allocation Thomas Gleixner <tglx@linutronix.de> - 2015-12-19 11:50 +0100
      Re: [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface  to manage Intel cache allocation Marcelo Tosatti <mtosatti@redhat.com> - 2015-12-21 13:00 +0100
        Re: [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface  to manage Intel cache allocation Thomas Gleixner <tglx@linutronix.de> - 2015-12-21 14:50 +0100
        Re: [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface  to manage Intel cache allocation Luiz Capitulino <lcapitulino@redhat.com> - 2015-12-21 16:50 +0100
          Re: [PATCH V16 11/11] x86,cgroup/intel_rdt : Add a cgroup interface  to manage Intel cache allocation Marcelo Tosatti <mtosatti@redhat.com> - 2015-12-22 00:10 +0100
  Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology  Support Christoph Lameter <cl@linux.com> - 2015-12-18 18:50 +0100
    Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology Support Marcelo Tosatti <mtosatti@redhat.com> - 2015-12-21 13:00 +0100
      Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology  Support Christoph Lameter <cl@linux.com> - 2015-12-21 14:00 +0100
  Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology  Support Luiz Capitulino <lcapitulino@redhat.com> - 2015-12-21 17:00 +0100
  Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology Support Tejun Heo <tj@kernel.org> - 2015-12-23 17:00 +0100

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