On Wed, Nov 09, 2016 at 05:39:51PM -0600, Jeremy Linton wrote:
> On systems with multiple PMU types the PMU to CPU affinity
> needs to be detected and set. The CPU to interrupt affinity
> should also be set.
>
> Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> ---
> drivers/perf/arm_pmu.c | 63 ++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 53 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index b37b572..6008be9 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -11,6 +11,7 @@
> */
> #define pr_fmt(fmt) "hw perfevents: " fmt
>
> +#include <linux/acpi.h>
> #include <linux/bitmap.h>
> #include <linux/cpumask.h>
> #include <linux/cpu_pm.h>
> @@ -24,6 +25,7 @@
> #include <linux/irq.h>
> #include <linux/irqdesc.h>
>
> +#include <asm/cpu.h>
> #include <asm/cputype.h>
> #include <asm/irq_regs.h>
>
> @@ -889,25 +891,67 @@ static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu)
> }
>
> /*
> - * CPU PMU identification and probing.
> + * CPU PMU identification and probing. Its possible to have
> + * multiple CPU types in an ARM machine. Assure that we are
> + * picking the right PMU types based on the CPU in question
> */
> -static int probe_current_pmu(struct arm_pmu *pmu,
> - const struct pmu_probe_info *info)
> +static int probe_plat_pmu(struct arm_pmu *pmu,
> + const struct pmu_probe_info *info,
> + unsigned int pmuid)
> {
> - int cpu = get_cpu();
> - unsigned int cpuid = read_cpuid_id();
> int ret = -ENODEV;
> + int cpu;
> + int aff_ctr = 0;
> + static int duplicate_pmus;
> + struct platform_device *pdev = pmu->plat_device;
> + int irq = platform_get_irq(pdev, 0);
>
> - pr_info("probing PMU on CPU %d\n", cpu);
> + if (irq >= 0 && !irq_is_percpu(irq)) {
> + pmu->irq_affinity = kcalloc(pdev->num_resources, sizeof(int),
> + GFP_KERNEL);
> + if (!pmu->irq_affinity)
> + return -ENOMEM;
> + }
>
> + for_each_possible_cpu(cpu) {
> + unsigned int cpuid = read_specific_cpuid(cpu);
> +
> + if (cpuid == pmuid) {
> + cpumask_set_cpu(cpu, &pmu->supported_cpus);
> + if (pmu->irq_affinity) {
> + pmu->irq_affinity[aff_ctr] = cpu;
> + aff_ctr++;
> + }
> + }
> + }
> +
> + /* find the type of PMU given the CPU */
> for (; info->init != NULL; info++) {
> - if ((cpuid & info->mask) != info->cpuid)
> + if ((pmuid & info->mask) != info->cpuid)
> continue;
> ret = info->init(pmu);
> + /*
> + * if this pmu declaration is unspecified and we have
> + * previously found a PMU on this platform then append
> + * a PMU number to the pmu name. This avoids changing
> + * the names of PMUs that are specific to a class of CPUs.
> + * The assumption is that if we match a specific PMU in the
> + * provided pmu_probe_info then it's unique, and another PMU
> + * in the system will match a different entry rather than
> + * needing the _number to assure its unique.
> + */
> + if ((!info->cpuid) && (duplicate_pmus)) {
This is a bit grim: if you had a PMU with a non-zero info->cpuid, then you
later found a PMU with a zeroed info->cpuid, the latter would get a
redundant suffix. This doesn't happen in reality, because the ACPI case
always has info->cpuid == 0, but if somebody extends armv8_pmu_probe_table
then we'd get this and probably not realise.
I think the duplicate_pmus counter needs to be tied explicitly to the
"default type" (i.e. when info->cpuid == 0, but see my next comment).
> + pmu->name = kasprintf(GFP_KERNEL, "%s_%d",
> + pmu->name, duplicate_pmus);
> + if (!pmu->name) {
> + kfree(pmu->irq_affinity);
> + ret = -ENOMEM;
> + }
> + }
This code doesn't run for the device-tree probing case, but I think it would
be useful to do the same numbering trick for e.g. systems with multiple PMUs
that all end up matching on armv8_pmuv3.
Will
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