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powerpc/perf/hv-24x7: Add cpu hotplug support 

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 <kjain@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200709051836.723765-2-kjain@linux.ibm.com
This commit is contained in:
Kajol Jain 2020-07-09 10:48:35 +05:30 committed by Michael Ellerman
parent e978a3ccaa
commit 1a8f0886a6
2 changed files with 47 additions and 0 deletions
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46
arch/powerpc/perf/hv-24x7.c
View File

@ -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;

1
include/linux/cpuhotplug.h
View File

@ -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,