diff options
Diffstat (limited to 'kernel/trace/trace_hwlat.c')
| -rw-r--r-- | kernel/trace/trace_hwlat.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index 65aab3914a56..b97286c48735 100644 --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -64,6 +64,15 @@ static struct dentry *hwlat_sample_window; /* sample window us */ /* Save the previous tracing_thresh value */ static unsigned long save_tracing_thresh; +/* NMI timestamp counters */ +static u64 nmi_ts_start; +static u64 nmi_total_ts; +static int nmi_count; +static int nmi_cpu; + +/* Tells NMIs to call back to the hwlat tracer to record timestamps */ +bool trace_hwlat_callback_enabled; + /* If the user changed threshold, remember it */ static u64 last_tracing_thresh = DEFAULT_LAT_THRESHOLD * NSEC_PER_USEC; @@ -72,7 +81,9 @@ struct hwlat_sample { u64 seqnum; /* unique sequence */ u64 duration; /* delta */ u64 outer_duration; /* delta (outer loop) */ + u64 nmi_total_ts; /* Total time spent in NMIs */ struct timespec timestamp; /* wall time */ + int nmi_count; /* # NMIs during this sample */ }; /* keep the global state somewhere. */ @@ -112,6 +123,8 @@ static void trace_hwlat_sample(struct hwlat_sample *sample) entry->duration = sample->duration; entry->outer_duration = sample->outer_duration; entry->timestamp = sample->timestamp; + entry->nmi_total_ts = sample->nmi_total_ts; + entry->nmi_count = sample->nmi_count; if (!call_filter_check_discard(call, entry, buffer, event)) __buffer_unlock_commit(buffer, event); @@ -125,6 +138,26 @@ static void trace_hwlat_sample(struct hwlat_sample *sample) #define init_time(a, b) (a = b) #define time_u64(a) a +void trace_hwlat_callback(bool enter) +{ + if (smp_processor_id() != nmi_cpu) + return; + + /* + * Currently trace_clock_local() calls sched_clock() and the + * generic version is not NMI safe. + */ + if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) { + if (enter) + nmi_ts_start = time_get(); + else + nmi_total_ts = time_get() - nmi_ts_start; + } + + if (enter) + nmi_count++; +} + /** * get_sample - sample the CPU TSC and look for likely hardware latencies * @@ -144,6 +177,14 @@ static int get_sample(void) do_div(thresh, NSEC_PER_USEC); /* modifies interval value */ + nmi_cpu = smp_processor_id(); + nmi_total_ts = 0; + nmi_count = 0; + /* Make sure NMIs see this first */ + barrier(); + + trace_hwlat_callback_enabled = true; + init_time(last_t2, 0); start = time_get(); /* start timestamp */ @@ -188,6 +229,10 @@ static int get_sample(void) } while (total <= hwlat_data.sample_width); + barrier(); /* finish the above in the view for NMIs */ + trace_hwlat_callback_enabled = false; + barrier(); /* Make sure nmi_total_ts is no longer updated */ + ret = 0; /* If we exceed the threshold value, we have found a hardware latency */ @@ -196,11 +241,17 @@ static int get_sample(void) ret = 1; + /* We read in microseconds */ + if (nmi_total_ts) + do_div(nmi_total_ts, NSEC_PER_USEC); + hwlat_data.count++; s.seqnum = hwlat_data.count; s.duration = sample; s.outer_duration = outer_sample; s.timestamp = CURRENT_TIME; + s.nmi_total_ts = nmi_total_ts; + s.nmi_count = nmi_count; trace_hwlat_sample(&s); /* Keep a running maximum ever recorded hardware latency */ |