Messages in this thread |  | | Subject | Re: [RFC 02/11] coresight: etm-perf: Allow an event to use different sinks | From | Suzuki K Poulose <> | Date | Thu, 12 Nov 2020 09:21:40 +0000 |
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Hi Linu,
Please could you test this slightly modified version and give us a Tested-by tag if you are happy with the results ?
Suzuki
On 11/10/20 12:45 PM, Anshuman Khandual wrote: > From: Suzuki K Poulose <suzuki.poulose@arm.com> > > When there are multiple sinks on the system, in the absence > of a specified sink, it is quite possible that a default sink > for an ETM could be different from that of another ETM. However > we do not support having multiple sinks for an event yet. This > patch allows the event to use the default sinks on the ETMs > where they are scheduled as long as the sinks are of the same > type. > > e.g, if we have 1x1 topology with per-CPU ETRs, the event can > use the per-CPU ETR for the session. However, if the sinks > are of different type, e.g TMC-ETR on one and a custom sink > on another, the event will only trace on the first detected > sink. > > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > drivers/hwtracing/coresight/coresight-etm-perf.c | 50 ++++++++++++++++++------ > 1 file changed, 39 insertions(+), 11 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c > index c2c9b12..ea73cfa 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > @@ -204,14 +204,22 @@ static void etm_free_aux(void *data) > schedule_work(&event_data->work); > } > > +static bool sinks_match(struct coresight_device *a, struct coresight_device *b) > +{ > + if (!a || !b) > + return false; > + return (sink_ops(a) == sink_ops(b)); > +} > + > static void *etm_setup_aux(struct perf_event *event, void **pages, > int nr_pages, bool overwrite) > { > u32 id; > int cpu = event->cpu; > cpumask_t *mask; > - struct coresight_device *sink; > + struct coresight_device *sink = NULL; > struct etm_event_data *event_data = NULL; > + bool sink_forced = false; > > event_data = alloc_event_data(cpu); > if (!event_data) > @@ -222,6 +230,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, > if (event->attr.config2) { > id = (u32)event->attr.config2; > sink = coresight_get_sink_by_id(id); > + sink_forced = true; > } > > mask = &event_data->mask; > @@ -235,7 +244,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, > */ > for_each_cpu(cpu, mask) { > struct list_head *path; > - struct coresight_device *csdev; > + struct coresight_device *csdev, *new_sink; > > csdev = per_cpu(csdev_src, cpu); > /* > @@ -249,21 +258,35 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, > } > > /* > - * No sink provided - look for a default sink for one of the > - * devices. At present we only support topology where all CPUs > - * use the same sink [N:1], so only need to find one sink. The > - * coresight_build_path later will remove any CPU that does not > - * attach to the sink, or if we have not found a sink. > + * No sink provided - look for a default sink for all the devices. > + * We only support multiple sinks, only if all the default sinks > + * are of the same type, so that the sink buffer can be shared > + * as the event moves around. We don't trace on a CPU if it can't > + * > */ > - if (!sink) > - sink = coresight_find_default_sink(csdev); > + if (!sink_forced) { > + new_sink = coresight_find_default_sink(csdev); > + if (!new_sink) { > + cpumask_clear_cpu(cpu, mask); > + continue; > + } > + /* Skip checks for the first sink */ > + if (!sink) { > + sink = new_sink; > + } else if (!sinks_match(new_sink, sink)) { > + cpumask_clear_cpu(cpu, mask); > + continue; > + } > + } else { > + new_sink = sink; > + } > > /* > * Building a path doesn't enable it, it simply builds a > * list of devices from source to sink that can be > * referenced later when the path is actually needed. > */ > - path = coresight_build_path(csdev, sink); > + path = coresight_build_path(csdev, new_sink); > if (IS_ERR(path)) { > cpumask_clear_cpu(cpu, mask); > continue; > @@ -284,7 +307,12 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, > if (!sink_ops(sink)->alloc_buffer || !sink_ops(sink)->free_buffer) > goto err; > > - /* Allocate the sink buffer for this session */ > + /* > + * Allocate the sink buffer for this session. All the sinks > + * where this event can be scheduled are ensured to be of the > + * same type. Thus the same sink configuration is used by the > + * sinks. > + */ > event_data->snk_config = > sink_ops(sink)->alloc_buffer(sink, event, pages, > nr_pages, overwrite); >
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