Re: [PATCH] perf_events: improve x86 event scheduling (v5)
From: Peter Zijlstra
Date: Mon Jan 18 2010 - 08:55:23 EST
On Mon, 2010-01-18 at 14:43 +0100, Frederic Weisbecker wrote:
> Shouldn't we actually use the core based pmu->enable(),disable()
> model called from kernel/perf_event.c:event_sched_in(),
> like every other events, where we can fill up the queue of hardware
> events to be scheduled, and then call a hw_check_constraints()
> when we finish a group scheduling?
Well the thing that makes hw_perf_group_sched_in() useful is that you
can add a bunch of events and not have to reschedule for each one, but
instead do a single schedule pass.
That said you do have a point, maybe we can express this particular
thing differently.. maybe a pre and post group call like:
void hw_perf_group_sched_in_begin(struct pmu *pmu)
int hw_perf_group_sched_in_end(struct pmu *pmu)
That way we know we need to track more state for rollback and can give
the pmu implementation leeway to delay scheduling/availablility tests.
Paul, would that work for you too?
Then there's still the question of having events of multiple hw pmus in
a single group, I'd be perfectly fine with saying that's not allowed,
what to others think?
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/