diff options
| -rw-r--r-- | Documentation/x86/intel_rdt_ui.txt | 22 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c | 304 |
2 files changed, 203 insertions, 123 deletions
diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt index f662d3c530e5..52b10945ff75 100644 --- a/Documentation/x86/intel_rdt_ui.txt +++ b/Documentation/x86/intel_rdt_ui.txt @@ -520,18 +520,24 @@ the pseudo-locked region: 2) Cache hit and miss measurements using model specific precision counters if available. Depending on the levels of cache on the system the pseudo_lock_l2 and pseudo_lock_l3 tracepoints are available. - WARNING: triggering this measurement uses from two (for just L2 - measurements) to four (for L2 and L3 measurements) precision counters on - the system, if any other measurements are in progress the counters and - their corresponding event registers will be clobbered. When a pseudo-locked region is created a new debugfs directory is created for it in debugfs as /sys/kernel/debug/resctrl/<newdir>. A single write-only file, pseudo_lock_measure, is present in this directory. The -measurement on the pseudo-locked region depends on the number, 1 or 2, -written to this debugfs file. Since the measurements are recorded with the -tracing infrastructure the relevant tracepoints need to be enabled before the -measurement is triggered. +measurement of the pseudo-locked region depends on the number written to this +debugfs file: +1 - writing "1" to the pseudo_lock_measure file will trigger the latency + measurement captured in the pseudo_lock_mem_latency tracepoint. See + example below. +2 - writing "2" to the pseudo_lock_measure file will trigger the L2 cache + residency (cache hits and misses) measurement captured in the + pseudo_lock_l2 tracepoint. See example below. +3 - writing "3" to the pseudo_lock_measure file will trigger the L3 cache + residency (cache hits and misses) measurement captured in the + pseudo_lock_l3 tracepoint. + +All measurements are recorded with the tracing infrastructure. This requires +the relevant tracepoints to be enabled before the measurement is triggered. Example of latency debugging interface: In this example a pseudo-locked region named "newlock" was created. Here is diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c index 33d7968f152a..d68836139cf9 100644 --- a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c +++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c @@ -27,6 +27,7 @@ #include <asm/intel_rdt_sched.h> #include <asm/perf_event.h> +#include "../../events/perf_event.h" /* For X86_CONFIG() */ #include "intel_rdt.h" #define CREATE_TRACE_POINTS @@ -107,16 +108,6 @@ static u64 get_prefetch_disable_bits(void) return 0; } -/* - * Helper to write 64bit value to MSR without tracing. Used when - * use of the cache should be restricted and use of registers used - * for local variables avoided. - */ -static inline void pseudo_wrmsrl_notrace(unsigned int msr, u64 val) -{ - __wrmsr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32)); -} - /** * pseudo_lock_minor_get - Obtain available minor number * @minor: Pointer to where new minor number will be stored @@ -925,7 +916,7 @@ static int measure_cycles_lat_fn(void *_plr) * The actual configuration of the event is set right before use in order * to use the X86_CONFIG macro. */ -static struct perf_event_attr __attribute__((unused)) perf_miss_attr = { +static struct perf_event_attr perf_miss_attr = { .type = PERF_TYPE_RAW, .size = sizeof(struct perf_event_attr), .pinned = 1, @@ -933,7 +924,7 @@ static struct perf_event_attr __attribute__((unused)) perf_miss_attr = { .exclude_user = 1, }; -static struct perf_event_attr __attribute__((unused)) perf_hit_attr = { +static struct perf_event_attr perf_hit_attr = { .type = PERF_TYPE_RAW, .size = sizeof(struct perf_event_attr), .pinned = 1, @@ -941,139 +932,215 @@ static struct perf_event_attr __attribute__((unused)) perf_hit_attr = { .exclude_user = 1, }; -static int measure_cycles_perf_fn(void *_plr) +struct residency_counts { + u64 miss_before, hits_before; + u64 miss_after, hits_after; +}; + +static int measure_residency_fn(struct perf_event_attr *miss_attr, + struct perf_event_attr *hit_attr, + struct pseudo_lock_region *plr, + struct residency_counts *counts) { - unsigned long long l3_hits = 0, l3_miss = 0; - u64 l3_hit_bits = 0, l3_miss_bits = 0; - struct pseudo_lock_region *plr = _plr; - unsigned long long l2_hits, l2_miss; - u64 l2_hit_bits, l2_miss_bits; + u64 hits_before = 0, hits_after = 0, miss_before = 0, miss_after = 0; + struct perf_event *miss_event, *hit_event; + int hit_pmcnum, miss_pmcnum; unsigned int line_size; unsigned int size; unsigned long i; void *mem_r; + u64 tmp; - /* - * Non-architectural event for the Goldmont Microarchitecture - * from Intel x86 Architecture Software Developer Manual (SDM): - * MEM_LOAD_UOPS_RETIRED D1H (event number) - * Umask values: - * L1_HIT 01H - * L2_HIT 02H - * L1_MISS 08H - * L2_MISS 10H - * - * On Broadwell Microarchitecture the MEM_LOAD_UOPS_RETIRED event - * has two "no fix" errata associated with it: BDM35 and BDM100. On - * this platform we use the following events instead: - * L2_RQSTS 24H (Documented in https://download.01.org/perfmon/BDW/) - * REFERENCES FFH - * MISS 3FH - * LONGEST_LAT_CACHE 2EH (Documented in SDM) - * REFERENCE 4FH - * MISS 41H - */ + miss_event = perf_event_create_kernel_counter(miss_attr, plr->cpu, + NULL, NULL, NULL); + if (IS_ERR(miss_event)) + goto out; + hit_event = perf_event_create_kernel_counter(hit_attr, plr->cpu, + NULL, NULL, NULL); + if (IS_ERR(hit_event)) + goto out_miss; + + local_irq_disable(); /* - * Start by setting flags for IA32_PERFEVTSELx: - * OS (Operating system mode) 0x2 - * INT (APIC interrupt enable) 0x10 - * EN (Enable counter) 0x40 - * - * Then add the Umask value and event number to select performance - * event. + * Check any possible error state of events used by performing + * one local read. */ - - switch (boot_cpu_data.x86_model) { - case INTEL_FAM6_ATOM_GOLDMONT: - case INTEL_FAM6_ATOM_GEMINI_LAKE: - l2_hit_bits = (0x52ULL << 16) | (0x2 << 8) | 0xd1; - l2_miss_bits = (0x52ULL << 16) | (0x10 << 8) | 0xd1; - break; - case INTEL_FAM6_BROADWELL_X: - /* On BDW the l2_hit_bits count references, not hits */ - l2_hit_bits = (0x52ULL << 16) | (0xff << 8) | 0x24; - l2_miss_bits = (0x52ULL << 16) | (0x3f << 8) | 0x24; - /* On BDW the l3_hit_bits count references, not hits */ - l3_hit_bits = (0x52ULL << 16) | (0x4f << 8) | 0x2e; - l3_miss_bits = (0x52ULL << 16) | (0x41 << 8) | 0x2e; - break; - default: - goto out; + if (perf_event_read_local(miss_event, &tmp, NULL, NULL)) { + local_irq_enable(); + goto out_hit; + } + if (perf_event_read_local(hit_event, &tmp, NULL, NULL)) { + local_irq_enable(); + goto out_hit; } - local_irq_disable(); /* * Disable hardware prefetchers. */ wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0); - /* Disable events and reset counters */ - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 1, 0x0); - if (l3_hit_bits > 0) { - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 2, 0x0); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 3, 0x0); - } - /* Set and enable the L2 counters */ + + /* Initialize rest of local variables */ + /* + * Performance event has been validated right before this with + * interrupts disabled - it is thus safe to read the counter index. + */ + miss_pmcnum = x86_perf_rdpmc_index(miss_event); + hit_pmcnum = x86_perf_rdpmc_index(hit_event); + line_size = READ_ONCE(plr->line_size); mem_r = READ_ONCE(plr->kmem); size = READ_ONCE(plr->size); - line_size = READ_ONCE(plr->line_size); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0, l2_hit_bits); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1, l2_miss_bits); - if (l3_hit_bits > 0) { - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2, - l3_hit_bits); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3, - l3_miss_bits); - } + + /* + * Read counter variables twice - first to load the instructions + * used in L1 cache, second to capture accurate value that does not + * include cache misses incurred because of instruction loads. + */ + rdpmcl(hit_pmcnum, hits_before); + rdpmcl(miss_pmcnum, miss_before); + /* + * From SDM: Performing back-to-back fast reads are not guaranteed + * to be monotonic. + * Use LFENCE to ensure all previous instructions are retired + * before proceeding. + */ + rmb(); + rdpmcl(hit_pmcnum, hits_before); + rdpmcl(miss_pmcnum, miss_before); + /* + * Use LFENCE to ensure all previous instructions are retired + * before proceeding. + */ + rmb(); for (i = 0; i < size; i += line_size) { + /* + * Add a barrier to prevent speculative execution of this + * loop reading beyond the end of the buffer. + */ + rmb(); asm volatile("mov (%0,%1,1), %%eax\n\t" : : "r" (mem_r), "r" (i) : "%eax", "memory"); } /* - * Call wrmsr directly (no tracing) to not influence - * the cache access counters as they are disabled. + * Use LFENCE to ensure all previous instructions are retired + * before proceeding. */ - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0, - l2_hit_bits & ~(0x40ULL << 16)); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1, - l2_miss_bits & ~(0x40ULL << 16)); - if (l3_hit_bits > 0) { - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2, - l3_hit_bits & ~(0x40ULL << 16)); - pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3, - l3_miss_bits & ~(0x40ULL << 16)); - } - l2_hits = native_read_pmc(0); - l2_miss = native_read_pmc(1); - if (l3_hit_bits > 0) { - l3_hits = native_read_pmc(2); - l3_miss = native_read_pmc(3); - } + rmb(); + rdpmcl(hit_pmcnum, hits_after); + rdpmcl(miss_pmcnum, miss_after); + /* + * Use LFENCE to ensure all previous instructions are retired + * before proceeding. + */ + rmb(); + /* Re-enable hardware prefetchers */ wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0); local_irq_enable(); +out_hit: + perf_event_release_kernel(hit_event); +out_miss: + perf_event_release_kernel(miss_event); +out: + /* + * All counts will be zero on failure. + */ + counts->miss_before = miss_before; + counts->hits_before = hits_before; + counts->miss_after = miss_after; + counts->hits_after = hits_after; + return 0; +} + +static int measure_l2_residency(void *_plr) +{ + struct pseudo_lock_region *plr = _plr; + struct residency_counts counts = {0}; + + /* + * Non-architectural event for the Goldmont Microarchitecture + * from Intel x86 Architecture Software Developer Manual (SDM): + * MEM_LOAD_UOPS_RETIRED D1H (event number) + * Umask values: + * L2_HIT 02H + * L2_MISS 10H + */ + switch (boot_cpu_data.x86_model) { + case INTEL_FAM6_ATOM_GOLDMONT: + case INTEL_FAM6_ATOM_GEMINI_LAKE: + perf_miss_attr.config = X86_CONFIG(.event = 0xd1, + .umask = 0x10); + perf_hit_attr.config = X86_CONFIG(.event = 0xd1, + .umask = 0x2); + break; + default: + goto out; + } + + measure_residency_fn(&perf_miss_attr, &perf_hit_attr, plr, &counts); + /* + * If a failure prevented the measurements from succeeding + * tracepoints will still be written and all counts will be zero. + */ + trace_pseudo_lock_l2(counts.hits_after - counts.hits_before, + counts.miss_after - counts.miss_before); +out: + plr->thread_done = 1; + wake_up_interruptible(&plr->lock_thread_wq); + return 0; +} + +static int measure_l3_residency(void *_plr) +{ + struct pseudo_lock_region *plr = _plr; + struct residency_counts counts = {0}; + /* - * On BDW we count references and misses, need to adjust. Sometimes - * the "hits" counter is a bit more than the references, for - * example, x references but x + 1 hits. To not report invalid - * hit values in this case we treat that as misses eaqual to - * references. + * On Broadwell Microarchitecture the MEM_LOAD_UOPS_RETIRED event + * has two "no fix" errata associated with it: BDM35 and BDM100. On + * this platform the following events are used instead: + * LONGEST_LAT_CACHE 2EH (Documented in SDM) + * REFERENCE 4FH + * MISS 41H */ - if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X) - l2_hits -= (l2_miss > l2_hits ? l2_hits : l2_miss); - trace_pseudo_lock_l2(l2_hits, l2_miss); - if (l3_hit_bits > 0) { - if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X) - l3_hits -= (l3_miss > l3_hits ? l3_hits : l3_miss); - trace_pseudo_lock_l3(l3_hits, l3_miss); + + switch (boot_cpu_data.x86_model) { + case INTEL_FAM6_BROADWELL_X: + /* On BDW the hit event counts references, not hits */ + perf_hit_attr.config = X86_CONFIG(.event = 0x2e, + .umask = 0x4f); + perf_miss_attr.config = X86_CONFIG(.event = 0x2e, + .umask = 0x41); + break; + default: + goto out; + } + + measure_residency_fn(&perf_miss_attr, &perf_hit_attr, plr, &counts); + /* + * If a failure prevented the measurements from succeeding + * tracepoints will still be written and all counts will be zero. + */ + + counts.miss_after -= counts.miss_before; + if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X) { + /* + * On BDW references and misses are counted, need to adjust. + * Sometimes the "hits" counter is a bit more than the + * references, for example, x references but x + 1 hits. + * To not report invalid hit values in this case we treat + * that as misses equal to references. + */ + /* First compute the number of cache references measured */ + counts.hits_after -= counts.hits_before; + /* Next convert references to cache hits */ + counts.hits_after -= min(counts.miss_after, counts.hits_after); + } else { + counts.hits_after -= counts.hits_before; } + trace_pseudo_lock_l3(counts.hits_after, counts.miss_after); out: plr->thread_done = 1; wake_up_interruptible(&plr->lock_thread_wq); @@ -1112,13 +1179,20 @@ static int pseudo_lock_measure_cycles(struct rdtgroup *rdtgrp, int sel) goto out; } + plr->cpu = cpu; + if (sel == 1) thread = kthread_create_on_node(measure_cycles_lat_fn, plr, cpu_to_node(cpu), "pseudo_lock_measure/%u", cpu); else if (sel == 2) - thread = kthread_create_on_node(measure_cycles_perf_fn, plr, + thread = kthread_create_on_node(measure_l2_residency, plr, + cpu_to_node(cpu), + "pseudo_lock_measure/%u", + cpu); + else if (sel == 3) + thread = kthread_create_on_node(measure_l3_residency, plr, cpu_to_node(cpu), "pseudo_lock_measure/%u", cpu); |