diff options
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event_p4.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_p4.c | 66 |
1 files changed, 30 insertions, 36 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c index 8b7a0c306784..7809d2bcb209 100644 --- a/arch/x86/kernel/cpu/perf_event_p4.c +++ b/arch/x86/kernel/cpu/perf_event_p4.c @@ -571,35 +571,34 @@ static __initconst const u64 p4_hw_cache_event_ids }; /* - * Because of Netburst being quite restricted in now - * many same events can run simultaneously, we use - * event aliases, ie different events which have the - * same functionallity but use non-intersected resources - * (ESCR/CCCR/couter registers). This allow us to run - * two or more semi-same events together. It is done - * transparently to a user space. + * Because of Netburst being quite restricted in how many + * identical events may run simultaneously, we introduce event aliases, + * ie the different events which have the same functionality but + * utilize non-intersected resources (ESCR/CCCR/counter registers). * - * Never set any cusom internal bits such as P4_CONFIG_HT, - * P4_CONFIG_ALIASABLE or bits for P4_PEBS_METRIC, they are - * either up-to-dated automatically either not appliable - * at all. + * This allow us to relax restrictions a bit and run two or more + * identical events together. * - * And be really carefull choosing aliases! + * Never set any custom internal bits such as P4_CONFIG_HT, + * P4_CONFIG_ALIASABLE or bits for P4_PEBS_METRIC, they are + * either up to date automatically or not applicable at all. */ struct p4_event_alias { - u64 orig; - u64 alter; + u64 original; + u64 alternative; } p4_event_aliases[] = { { /* - * Non-halted cycles can be substituted with - * non-sleeping cycles (see Intel SDM Vol3b for - * details). + * Non-halted cycles can be substituted with non-sleeping cycles (see + * Intel SDM Vol3b for details). We need this alias to be able + * to run nmi-watchdog and 'perf top' (or any other user space tool + * which is interested in running PERF_COUNT_HW_CPU_CYCLES) + * simultaneously. */ - .orig = + .original = p4_config_pack_escr(P4_ESCR_EVENT(P4_EVENT_GLOBAL_POWER_EVENTS) | P4_ESCR_EMASK_BIT(P4_EVENT_GLOBAL_POWER_EVENTS, RUNNING)), - .alter = + .alternative = p4_config_pack_escr(P4_ESCR_EVENT(P4_EVENT_EXECUTION_EVENT) | P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS0)| P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS1)| @@ -620,25 +619,21 @@ static u64 p4_get_alias_event(u64 config) int i; /* - * Probably we're lucky and don't have to do - * matching over all config bits. + * Only event with special mark is allowed, + * we're to be sure it didn't come as malformed + * RAW event. */ if (!(config & P4_CONFIG_ALIASABLE)) return 0; config_match = config & P4_CONFIG_EVENT_ALIAS_MASK; - /* - * If an event was previously swapped to the alter config - * we should swap it back otherwise contnention on registers - * will return back. - */ for (i = 0; i < ARRAY_SIZE(p4_event_aliases); i++) { - if (config_match == p4_event_aliases[i].orig) { - config_match = p4_event_aliases[i].alter; + if (config_match == p4_event_aliases[i].original) { + config_match = p4_event_aliases[i].alternative; break; - } else if (config_match == p4_event_aliases[i].alter) { - config_match = p4_event_aliases[i].orig; + } else if (config_match == p4_event_aliases[i].alternative) { + config_match = p4_event_aliases[i].original; break; } } @@ -646,8 +641,7 @@ static u64 p4_get_alias_event(u64 config) if (i >= ARRAY_SIZE(p4_event_aliases)) return 0; - return config_match | - (config & P4_CONFIG_EVENT_ALIAS_IMMUTABLE_BITS); + return config_match | (config & P4_CONFIG_EVENT_ALIAS_IMMUTABLE_BITS); } static u64 p4_general_events[PERF_COUNT_HW_MAX] = { @@ -1229,9 +1223,9 @@ static int p4_pmu_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign again: /* - * Aliases are swappable so we may hit circular - * lock if both original config and alias need - * resources (MSR registers) which already busy. + * It's possible to hit a circular lock + * between original and alternative events + * if both are scheduled already. */ if (pass > 2) goto done; @@ -1251,7 +1245,7 @@ again: cntr_idx = p4_next_cntr(thread, used_mask, bind); if (cntr_idx == -1 || test_bit(escr_idx, escr_mask)) { /* - * Probably an event alias is still available. + * Check whether an event alias is still available. */ config_alias = p4_get_alias_event(hwc->config); if (!config_alias) |