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Subject[patch V2 15/67] perf/x86/intel/cqm: Convert Intel CQM to hotplug state machine
From: Richard Cochran <rcochran@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
arch/x86/events/intel/cqm.c | 49 +++++++++++++++++----------------------------
include/linux/cpuhotplug.h | 2 ++
2 files changed, 20 insertions(+), 31 deletions(-)

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 7b5fd81..783c49d 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -1577,7 +1577,7 @@ static inline void cqm_pick_event_reader(int cpu)
cpumask_set_cpu(cpu, &cqm_cpumask);
}

-static void intel_cqm_cpu_starting(unsigned int cpu)
+static int intel_cqm_cpu_starting(unsigned int cpu)
{
struct intel_pqr_state *state = &per_cpu(pqr_state, cpu);
struct cpuinfo_x86 *c = &cpu_data(cpu);
@@ -1588,39 +1588,26 @@ static void intel_cqm_cpu_starting(unsigned int cpu)

WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);
WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale);
+
+ cqm_pick_event_reader(cpu);
+ return 0;
}

-static void intel_cqm_cpu_exit(unsigned int cpu)
+static int intel_cqm_cpu_exit(unsigned int cpu)
{
int target;

/* Is @cpu the current cqm reader for this package ? */
if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask))
- return;
+ return 0;

/* 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,
- unsigned long action, void *hcpu)
-{
- unsigned int cpu = (unsigned long)hcpu;
-
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_PREPARE:
- intel_cqm_cpu_exit(cpu);
- break;
- case CPU_STARTING:
- intel_cqm_cpu_starting(cpu);
- cqm_pick_event_reader(cpu);
- break;
- }

- return NOTIFY_OK;
+ return 0;
}

static const struct x86_cpu_id intel_cqm_match[] = {
@@ -1682,7 +1669,7 @@ out:
static int __init intel_cqm_init(void)
{
char *str = NULL, scale[20];
- int i, cpu, ret;
+ int cpu, ret;

if (x86_match_cpu(intel_cqm_match))
cqm_enabled = true;
@@ -1705,8 +1692,7 @@ static int __init intel_cqm_init(void)
*
* Also, check that the scales match on all cpus.
*/
- cpu_notifier_register_begin();
-
+ get_online_cpus();
for_each_online_cpu(cpu) {
struct cpuinfo_x86 *c = &cpu_data(cpu);

@@ -1743,11 +1729,6 @@ static int __init intel_cqm_init(void)
if (ret)
goto out;

- for_each_online_cpu(i) {
- intel_cqm_cpu_starting(i);
- cqm_pick_event_reader(i);
- }
-
if (mbm_enabled)
ret = intel_mbm_init();
if (ret && !cqm_enabled)
@@ -1772,12 +1753,18 @@ static int __init intel_cqm_init(void)
pr_info("Intel MBM enabled\n");

/*
- * Register the hot cpu notifier once we are sure cqm
+ * Setup the hot cpu notifier once we are sure cqm
* is enabled to avoid notifier leak.
*/
- __perf_cpu_notifier(intel_cqm_cpu_notifier);
+ cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_STARTING,
+ "AP_PERF_X86_CQM_STARTING",
+ intel_cqm_cpu_starting, NULL);
+ cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_ONLINE, "AP_PERF_X86_CQM_ONLINE",
+ NULL, intel_cqm_cpu_exit);
+
out:
- cpu_notifier_register_done();
+ put_online_cpus();
+
if (ret) {
kfree(str);
cqm_cleanup();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 06d77fd..f9399ee 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -25,6 +25,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
CPUHP_AP_PERF_X86_STARTING,
CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
+ CPUHP_AP_PERF_X86_CQM_STARTING,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,
CPUHP_TEARDOWN_CPU,
@@ -36,6 +37,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_X86_UNCORE_ONLINE,
CPUHP_AP_PERF_X86_AMD_UNCORE_ONLINE,
CPUHP_AP_PERF_X86_RAPL_ONLINE,
+ CPUHP_AP_PERF_X86_CQM_ONLINE,
CPUHP_AP_NOTIFY_ONLINE,
CPUHP_AP_ONLINE_DYN,
CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
--
2.8.1


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