Patch here adds cpu hotplug functions to hv_24x7 pmu.
A new cpuhp_state "CPUHP_AP_PERF_POWERPC_HV_24x7_ONLINE" enum
is added.
The online callback function updates the cpumask only if its
empty. As the primary intention of adding hotplug support
is to designate a CPU to make HCALL to collect the
counter data.
The offline function test and clear corresponding cpu in a cpumask
and update cpumask to any other active cpu.
Signed-off-by: Kajol Jain <kj...@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
---
arch/powerpc/perf/hv-24x7.c | 46 +++++++++++++++++++++++++++++++++++++
include/linux/cpuhotplug.h | 1 +
2 files changed, 47 insertions(+)
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index db213eb7cb02..93b4700dcf8c 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -31,6 +31,8 @@ static int interface_version;
/* Whether we have to aggregate result data for some domains. */
static bool aggregate_result_elements;
+static cpumask_t hv_24x7_cpumask;
+
static bool domain_is_valid(unsigned domain)
{
switch (domain) {
@@ -1641,6 +1643,45 @@ static struct pmu h_24x7_pmu = {
.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
};
+static int ppc_hv_24x7_cpu_online(unsigned int cpu)
+{
+ if (cpumask_empty(&hv_24x7_cpumask))
+ cpumask_set_cpu(cpu, &hv_24x7_cpumask);
+
+ return 0;
+}
+
+static int ppc_hv_24x7_cpu_offline(unsigned int cpu)
+{
+ int target;
+
+ /* Check if exiting cpu is used for collecting 24x7 events */
+ if (!cpumask_test_and_clear_cpu(cpu, &hv_24x7_cpumask))
+ return 0;
+
+ /* Find a new cpu to collect 24x7 events */
+ target = cpumask_last(cpu_active_mask);
+
+ if (target < 0 || target >= nr_cpu_ids) {
+ pr_err("hv_24x7: CPU hotplug init failed\n");
+ return -1;
+ }
+
+ /* Migrate 24x7 events to the new target */
+ cpumask_set_cpu(target, &hv_24x7_cpumask);
+ perf_pmu_migrate_context(&h_24x7_pmu, cpu, target);
+
+ return 0;
+}
+
+static int hv_24x7_cpu_hotplug_init(void)
+{
+ return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_HV_24x7_ONLINE,
+ "perf/powerpc/hv_24x7:online",
+ ppc_hv_24x7_cpu_online,
+ ppc_hv_24x7_cpu_offline);
+}
+
static int hv_24x7_init(void)
{
int r;
@@ -1685,6 +1726,11 @@ static int hv_24x7_init(void)
if (r)
return r;
+ /* init cpuhotplug */
+ r = hv_24x7_cpu_hotplug_init();
+ if (r)
+ return r;
+
r = perf_pmu_register(&h_24x7_pmu, h_24x7_pmu.name, -1);
if (r)
return r;
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 191772d4a4d7..a2710e654b64 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -181,6 +181,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
+ CPUHP_AP_PERF_POWERPC_HV_24x7_ONLINE,
CPUHP_AP_WATCHDOG_ONLINE,
CPUHP_AP_WORKQUEUE_ONLINE,
CPUHP_AP_RCUTREE_ONLINE,
--
2.26.2
