unimore/kernel-hacking-2024-linux-steffo
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perfcounters: add fixed-mode PMC enumeration

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Enumerate fixed-mode PMCs based on CPUID, and feed that into the
perfcounter code.

Does not use fixed-mode PMCs yet.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2008-12-17 10:51:15 +01:00
parent eb2b861810
commit 703e937c83
2 changed files with 40 additions and 6 deletions
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23
arch/x86/include/asm/perf_counter.h
View file

@ -41,6 +41,29 @@ union cpuid10_eax {
unsigned int full;
};
union cpuid10_edx {
struct {
unsigned int num_counters_fixed:4;
unsigned int reserved:28;
} split;
unsigned int full;
};
/*
* Fixed-purpose performance counters:
*/
/* Instr_Retired.Any: */
#define MSR_ARCH_PERFMON_FIXED_CTR0 0x309
/* CPU_CLK_Unhalted.Core: */
#define MSR_ARCH_PERFMON_FIXED_CTR1 0x30a
/* CPU_CLK_Unhalted.Ref: */
#define MSR_ARCH_PERFMON_FIXED_CTR2 0x30b
#ifdef CONFIG_PERF_COUNTERS
extern void init_hw_perf_counters(void);
extern void perf_counters_lapic_init(int nmi);

23
arch/x86/kernel/cpu/perf_counter.c
View file

@ -27,6 +27,8 @@ static bool perf_counters_initialized __read_mostly;
static int nr_hw_counters __read_mostly;
static u32 perf_counter_mask __read_mostly;
static int nr_hw_counters_fixed __read_mostly;
struct cpu_hw_counters {
struct perf_counter *generic[X86_PMC_MAX_GENERIC];
unsigned long used[BITS_TO_LONGS(X86_PMC_MAX_GENERIC)];
@ -519,8 +521,9 @@ static __read_mostly struct notifier_block perf_counter_nmi_notifier = {
void __init init_hw_perf_counters(void)
{
union cpuid10_eax eax;
unsigned int unused;
unsigned int ebx;
unsigned int unused;
union cpuid10_edx edx;
if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
return;
@ -529,14 +532,14 @@ void __init init_hw_perf_counters(void)
* Check whether the Architectural PerfMon supports
* Branch Misses Retired Event or not.
*/
cpuid(10, &(eax.full), &ebx, &unused, &unused);
cpuid(10, &eax.full, &ebx, &unused, &edx.full);
if (eax.split.mask_length <= ARCH_PERFMON_BRANCH_MISSES_RETIRED)
return;
printk(KERN_INFO "Intel Performance Monitoring support detected.\n");
printk(KERN_INFO "... version: %d\n", eax.split.version_id);
printk(KERN_INFO "... num_counters: %d\n", eax.split.num_counters);
printk(KERN_INFO "... version: %d\n", eax.split.version_id);
printk(KERN_INFO "... num counters: %d\n", eax.split.num_counters);
nr_hw_counters = eax.split.num_counters;
if (nr_hw_counters > X86_PMC_MAX_GENERIC) {
nr_hw_counters = X86_PMC_MAX_GENERIC;
@ -546,8 +549,16 @@ void __init init_hw_perf_counters(void)
perf_counter_mask = (1 << nr_hw_counters) - 1;
perf_max_counters = nr_hw_counters;
printk(KERN_INFO "... bit_width: %d\n", eax.split.bit_width);
printk(KERN_INFO "... mask_length: %d\n", eax.split.mask_length);
printk(KERN_INFO "... bit width: %d\n", eax.split.bit_width);
printk(KERN_INFO "... mask length: %d\n", eax.split.mask_length);
nr_hw_counters_fixed = edx.split.num_counters_fixed;
if (nr_hw_counters_fixed > X86_PMC_MAX_FIXED) {
nr_hw_counters_fixed = X86_PMC_MAX_FIXED;
WARN(1, KERN_ERR "hw perf counters fixed %d > max(%d), clipping!",
nr_hw_counters_fixed, X86_PMC_MAX_FIXED);
}
printk(KERN_INFO "... fixed counters: %d\n", nr_hw_counters_fixed);
perf_counters_initialized = true;