diff options
Diffstat (limited to 'arch/s390/kernel/perf_cpum_sf.c')
-rw-r--r-- | arch/s390/kernel/perf_cpum_sf.c | 45 |
1 files changed, 36 insertions, 9 deletions
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c index 96e4fcad57bf..c62eb09b2ba7 100644 --- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -185,7 +185,7 @@ static int realloc_sampling_buffer(struct sf_buffer *sfb, unsigned long num_sdb, gfp_t gfp_flags) { int i, rc; - unsigned long *new, *tail; + unsigned long *new, *tail, *tail_prev = NULL; if (!sfb->sdbt || !sfb->tail) return -EINVAL; @@ -224,6 +224,7 @@ static int realloc_sampling_buffer(struct sf_buffer *sfb, sfb->num_sdbt++; /* Link current page to tail of chain */ *tail = (unsigned long)(void *) new + 1; + tail_prev = tail; tail = new; } @@ -233,10 +234,22 @@ static int realloc_sampling_buffer(struct sf_buffer *sfb, * issue, a new realloc call (if required) might succeed. */ rc = alloc_sample_data_block(tail, gfp_flags); - if (rc) + if (rc) { + /* Undo last SDBT. An SDBT with no SDB at its first + * entry but with an SDBT entry instead can not be + * handled by the interrupt handler code. + * Avoid this situation. + */ + if (tail_prev) { + sfb->num_sdbt--; + free_page((unsigned long) new); + tail = tail_prev; + } break; + } sfb->num_sdb++; tail++; + tail_prev = new = NULL; /* Allocated at least one SBD */ } /* Link sampling buffer to its origin */ @@ -1282,18 +1295,28 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all) */ if (flush_all && done) break; - - /* If an event overflow happened, discard samples by - * processing any remaining sample-data-blocks. - */ - if (event_overflow) - flush_all = 1; } /* Account sample overflows in the event hardware structure */ if (sampl_overflow) OVERFLOW_REG(hwc) = DIV_ROUND_UP(OVERFLOW_REG(hwc) + sampl_overflow, 1 + num_sdb); + + /* Perf_event_overflow() and perf_event_account_interrupt() limit + * the interrupt rate to an upper limit. Roughly 1000 samples per + * task tick. + * Hitting this limit results in a large number + * of throttled REF_REPORT_THROTTLE entries and the samples + * are dropped. + * Slightly increase the interval to avoid hitting this limit. + */ + if (event_overflow) { + SAMPL_RATE(hwc) += DIV_ROUND_UP(SAMPL_RATE(hwc), 10); + debug_sprintf_event(sfdbg, 1, "%s: rate adjustment %ld\n", + __func__, + DIV_ROUND_UP(SAMPL_RATE(hwc), 10)); + } + if (sampl_overflow || event_overflow) debug_sprintf_event(sfdbg, 4, "hw_perf_event_update: " "overflow stats: sample=%llu event=%llu\n", @@ -1611,14 +1634,17 @@ static int __init init_cpum_sampling_pmu(void) } sfdbg = debug_register(KMSG_COMPONENT, 2, 1, 80); - if (!sfdbg) + if (!sfdbg) { pr_err("Registering for s390dbf failed\n"); + return -ENOMEM; + } debug_register_view(sfdbg, &debug_sprintf_view); err = register_external_irq(EXT_IRQ_MEASURE_ALERT, cpumf_measurement_alert); if (err) { pr_cpumsf_err(RS_INIT_FAILURE_ALRT); + debug_unregister(sfdbg); goto out; } @@ -1627,6 +1653,7 @@ static int __init init_cpum_sampling_pmu(void) pr_cpumsf_err(RS_INIT_FAILURE_PERF); unregister_external_irq(EXT_IRQ_MEASURE_ALERT, cpumf_measurement_alert); + debug_unregister(sfdbg); goto out; } |