Quoting Andi Shyti (2020-04-22 23:45:29)
> Hi Chris,
>
> [...]
>
> > +static int s_many(void *arg)
> > +{
> > + struct perf_series *ps = arg;
>
> why do we need to go through void... all functions are taking a
> perf_series structure.
The kthread API defines the function pointer as int (*fn)(void *arg);
>
> > + IGT_TIMEOUT(end_time);
> > + unsigned int idx = 0;
> > +
>
> [...]
>
> > + for (idx = 0; idx < nengines; idx++) {
> > + struct perf_stats *p =
> > + memset(&stats[idx], 0, sizeof(stats[idx]));
> > + struct intel_context *ce = ps->ce[idx];
> > +
> > + p->engine = ps->ce[idx]->engine;
> > + intel_engine_pm_get(p->engine);
> > +
> > + if (intel_engine_supports_stats(p->engine) &&
> > + !intel_enable_engine_stats(p->engine))
> > + p->busy = intel_engine_get_busy_time(p->engine) + 1;
> > + p->runtime = -intel_context_get_total_runtime_ns(ce);
> > + p->time = ktime_get();
> > + }
> > +
> > + err = (*fn)(ps);
> > + if (igt_live_test_end(&t))
> > + err = -EIO;
> > +
> > + for (idx = 0; idx < nengines; idx++) {
> > + struct perf_stats *p = &stats[idx];
> > + struct intel_context *ce = ps->ce[idx];
> > + int integer, decimal;
> > + u64 busy, dt;
> > +
> > + p->time = ktime_sub(ktime_get(), p->time);
> > + if (p->busy) {
> > + p->busy = ktime_sub(intel_engine_get_busy_time(p->engine),
> > + p->busy - 1);
> > + intel_disable_engine_stats(p->engine);
> > + }
> > +
> > + err = switch_to_kernel_sync(ce, err);
>
> how about err?
It's a case of where we need to flush all the engines regardless of the
error, so we wait until the end.
> > + p->runtime += intel_context_get_total_runtime_ns(ce);
>
> assigning a negative value to an unsigned so that you can add it
> later? looks nice but odd :)
>
> It's easier to understand if we do
>
> p->runtime = intel_context_get_total_runtime_ns(ce) - p->runtime;
>
> if you like it, no need to change, though.
I've done both. I'm fond of the unsigned addition of a negative number.
It's a few instructions less. :-p
>
> [...]
>
> > +static int p_many(void *arg)
> > +{
> > + struct perf_stats *p = arg;
> > + struct intel_engine_cs *engine = p->engine;
> > + struct intel_context *ce;
> > + IGT_TIMEOUT(end_time);
> > + unsigned long count;
> > + int err = 0;
> > + bool busy;
> > +
> > + ce = intel_context_create(engine);
> > + if (IS_ERR(ce))
> > + return PTR_ERR(ce);
> > +
> > + err = intel_context_pin(ce);
> > + if (err) {
> > + intel_context_put(ce);
> > + return err;
> > + }
> > +
> > + busy = false;
> > + if (intel_engine_supports_stats(engine) &&
> > + !intel_enable_engine_stats(engine)) {
> > + p->busy = intel_engine_get_busy_time(engine);
> > + busy = true;
> > + }
> > +
> > + count = 0;
> > + p->time = ktime_get();
> > + do {
> > + struct i915_request *rq;
> > +
> > + rq = i915_request_create(ce);
> > + if (IS_ERR(rq)) {
> > + err = PTR_ERR(rq);
> > + break;
> > + }
> > +
> > + i915_request_add(rq);
>
> do we need a request_put as well?
No. Nasty API, add consumes the reference. It's on the list to update
now that we have a ~majority of cases that want to keep a reference to
their request.
>
> > + count++;
> > + } while (!__igt_timeout(end_time, NULL));
> > + p->time = ktime_sub(ktime_get(), p->time);
> > +
> > + if (busy) {
> > + p->busy = ktime_sub(intel_engine_get_busy_time(engine),
> > + p->busy);
> > + intel_disable_engine_stats(engine);
> > + }
> > +
> > + err = switch_to_kernel_sync(ce, err);
> > + p->runtime = intel_context_get_total_runtime_ns(ce);
> > + p->count = count;
> > +
> > + intel_context_unpin(ce);
> > + intel_context_put(ce);
> > + return err;
> > +}
>
> [...]
>
> > + for_each_uabi_engine(engine, i915) {
> > + int status;
> > +
> > + if (IS_ERR(engines[idx].tsk))
> > + break;
>
> if we break here aren't we missing engine_pm_put and put_task?
No. We broke in the earlier loop as well, so the ERR_PTR is the
sentinel, indicating the end of the assignments.
-Chris
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