Hi Adrian,
On 11/26/2020 2:51 PM, Adrian Hunter wrote:
On 26/11/20 5:24 am, Jin Yao wrote:
When unpacking the event which is from dynamic pmu, the array
output[OUTPUT_TYPE_MAX] may be overrun. For example, type number of
SKL uncore_imc is 10, but OUTPUT_TYPE_MAX is 7 now (OUTPUT_TYPE_MAX =
PERF_TYPE_MAX + 1).
/* In builtin-script.c */
process_event()
{
unsigned int type = output_type(attr->type);
if (output[type].fields == 0)
return;
}
output[10] is overrun.
Create a type OUTPUT_TYPE_OTHER for dynamic pmu events, then
output_type(attr->type) will return OUTPUT_TYPE_OTHER here.
Note that if PERF_TYPE_MAX ever changed, then there would be a conflict
between old perf.data files that had a dynamicaliy allocated PMU number
that would then be the same as a fixed PERF_TYPE.
Example:
perf record --switch-events -C 0 -e
"{cpu-clock,uncore_imc/data_reads/,uncore_imc/data_writes/}:SD" -a -- sleep 1
perf script
Before:
swapper 0 [000] 1479253.987551: 277766
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.987797: 246709
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988127: 329883
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988273: 146393
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988523: 249977
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988877: 354090
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989023: 145940
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989383: 359856
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989523: 140082
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
After:
swapper 0 [000] 1397040.402011: 272384
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402011: 5396
uncore_imc/data_reads/:
swapper 0 [000] 1397040.402011: 967
uncore_imc/data_writes/:
swapper 0 [000] 1397040.402259: 249153
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402259: 7231
uncore_imc/data_reads/:
swapper 0 [000] 1397040.402259: 1297
uncore_imc/data_writes/:
swapper 0 [000] 1397040.402508: 249108
cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402508: 5333
uncore_imc/data_reads/:
swapper 0 [000] 1397040.402508: 1008
uncore_imc/data_writes/:
Fixes: 1405720d4f26 ("perf script: Add 'synth' event type for synthesized
events")
It does not look to me like the problem was introduced by that commit. Are
you sure this Fixes tag is correct?
Commit 1405720d4f26 added the change:
@@ -1215,8 +1253,9 @@ static void process_event(struct perf_script *script,
{
struct thread *thread = al->thread;
struct perf_event_attr *attr = &evsel->attr;
+ unsigned int type = output_type(attr->type);
- if (output[attr->type].fields == 0)
+ if (output[type].fields == 0)
return;
But of course, we can also say the original "output[attr->type].fields" introduced the issue, I'm
not sure. Maybe Arnaldo can help to make the decision. :)
Thanks
Jin Yao
