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;
sfb->num_sdbt++;
/* Link current page to tail of chain */
*tail = (unsigned long)(void *) new + 1;
+ tail_prev = tail;
tail = new;
}
* 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 */
goto out;
}
+ if (si.ribm & CPU_MF_SF_RIBM_NOTAV) {
+ pr_warn("CPU Measurement Facility sampling is temporarily not available\n");
+ err = -EBUSY;
+ goto out;
+ }
+
/* Always enable basic sampling */
SAMPL_FLAGS(hwc) = PERF_CPUM_SF_BASIC_MODE;
*/
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",