[PATCH V10 4/6] arm: arm64: pmu: Assign platform PMU CPU affinity
From: Will Deacon <hidden>
Date: 2016-11-29 10:52:55
Also in:
linux-acpi
On Wed, Nov 09, 2016 at 05:39:51PM -0600, Jeremy Linton wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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