| Message ID | 20210914102641.1852544-8-suzuki.poulose@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: TRBE and Self-Hosted trace fixes | expand |
On 9/14/21 3:56 PM, Suzuki K Poulose wrote: > The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ > on FILL event. This has rather unwanted side-effect of the event > being disabled when there may be more space in the ring buffer. > > So, instead of TRUNCATE we need a different flag to indicate > that the trace may have lost a few bytes (i.e from the point of > generating the FILL event until the IRQ is consumed). Anyways, the > userspace must use the size from RECORD_AUX headers to restrict > the "trace" decoding. > > Using PARTIAL flag causes the perf tool to generate the > following warning: > > Warning: > AUX data had gaps in it XX times out of YY! > > Are you running a KVM guest in the background? > > which is pointlessly scary for a user. The other remaining options > are : > - COLLISION - Use by SPE to indicate samples collided > - Add a new flag - Specifically for CoreSight, doesn't sound > so good, if we can re-use something. > > Given that we don't already use the "COLLISION" flag, the above > behavior can be notified using this flag for CoreSight. > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Cc: James Clark <james.clark@arm.com> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > Cc: Leo Yan <leo.yan@linaro.org> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > Changes since v2: > - The perf tool patch for reporting collisions is queued. > --- > drivers/hwtracing/coresight/coresight-trbe.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index de99dd0aecd3..a1a15fa6c4ae 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -612,7 +612,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, > * for correct size. Also, mark the buffer truncated. > */ > write = get_trbe_limit_pointer(); > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); > } > > offset = write - base; > @@ -705,7 +705,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > * Mark the buffer as truncated, as we have stopped the trace > * collection upon the WRAP event, without stopping the source. > */ > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); > perf_aux_output_end(handle, size); > event_data = perf_aux_output_begin(handle, event); > if (!event_data) { >
On Tue, Sep 14, 2021 at 11:26:38AM +0100, Suzuki K Poulose wrote: > The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ > on FILL event. This has rather unwanted side-effect of the event > being disabled when there may be more space in the ring buffer. > > So, instead of TRUNCATE we need a different flag to indicate > that the trace may have lost a few bytes (i.e from the point of > generating the FILL event until the IRQ is consumed). Anyways, the > userspace must use the size from RECORD_AUX headers to restrict > the "trace" decoding. > > Using PARTIAL flag causes the perf tool to generate the > following warning: > > Warning: > AUX data had gaps in it XX times out of YY! > > Are you running a KVM guest in the background? > > which is pointlessly scary for a user. The other remaining options > are : > - COLLISION - Use by SPE to indicate samples collided > - Add a new flag - Specifically for CoreSight, doesn't sound > so good, if we can re-use something. > > Given that we don't already use the "COLLISION" flag, the above > behavior can be notified using this flag for CoreSight. > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Cc: James Clark <james.clark@arm.com> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > Cc: Leo Yan <leo.yan@linaro.org> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > Changes since v2: > - The perf tool patch for reporting collisions is queued. > --- > drivers/hwtracing/coresight/coresight-trbe.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index de99dd0aecd3..a1a15fa6c4ae 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -612,7 +612,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, > * for correct size. Also, mark the buffer truncated. > */ > write = get_trbe_limit_pointer(); > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); The rational in the changelog should be added here as a comment. > } > > offset = write - base; > @@ -705,7 +705,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > * Mark the buffer as truncated, as we have stopped the trace > * collection upon the WRAP event, without stopping the source. > */ > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); Same. > perf_aux_output_end(handle, size); > event_data = perf_aux_output_begin(handle, event); > if (!event_data) { > -- > 2.24.1 >
On Tue, Sep 21, 2021 at 11:41:10AM -0600, Mathieu Poirier wrote: > On Tue, Sep 14, 2021 at 11:26:38AM +0100, Suzuki K Poulose wrote: > > The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ > > on FILL event. This has rather unwanted side-effect of the event > > being disabled when there may be more space in the ring buffer. > > > > So, instead of TRUNCATE we need a different flag to indicate > > that the trace may have lost a few bytes (i.e from the point of > > generating the FILL event until the IRQ is consumed). Anyways, the > > userspace must use the size from RECORD_AUX headers to restrict > > the "trace" decoding. > > > > Using PARTIAL flag causes the perf tool to generate the > > following warning: > > > > Warning: > > AUX data had gaps in it XX times out of YY! > > > > Are you running a KVM guest in the background? > > > > which is pointlessly scary for a user. The other remaining options > > are : > > - COLLISION - Use by SPE to indicate samples collided > > - Add a new flag - Specifically for CoreSight, doesn't sound > > so good, if we can re-use something. > > > > Given that we don't already use the "COLLISION" flag, the above > > behavior can be notified using this flag for CoreSight. > > > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > > Cc: James Clark <james.clark@arm.com> > > Cc: Mike Leach <mike.leach@linaro.org> > > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > > Cc: Leo Yan <leo.yan@linaro.org> > > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > > --- > > Changes since v2: > > - The perf tool patch for reporting collisions is queued. > > --- > > drivers/hwtracing/coresight/coresight-trbe.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > > index de99dd0aecd3..a1a15fa6c4ae 100644 > > --- a/drivers/hwtracing/coresight/coresight-trbe.c > > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > > @@ -612,7 +612,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, > > * for correct size. Also, mark the buffer truncated. > > */ > > write = get_trbe_limit_pointer(); > > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); > > The rational in the changelog should be added here as a comment. > > > } > > > > offset = write - base; > > @@ -705,7 +705,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > > * Mark the buffer as truncated, as we have stopped the trace > > * collection upon the WRAP event, without stopping the source. > > */ > > - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > > + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); > > Same. ... and I'm out of time for today. I will continue tomorrow. Thanks, Mathieu > > > perf_aux_output_end(handle, size); > > event_data = perf_aux_output_begin(handle, event); > > if (!event_data) { > > -- > > 2.24.1 > >
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index de99dd0aecd3..a1a15fa6c4ae 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -612,7 +612,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, * for correct size. Also, mark the buffer truncated. */ write = get_trbe_limit_pointer(); - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); } offset = write - base; @@ -705,7 +705,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) * Mark the buffer as truncated, as we have stopped the trace * collection upon the WRAP event, without stopping the source. */ - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); perf_aux_output_end(handle, size); event_data = perf_aux_output_begin(handle, event); if (!event_data) {
The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ on FILL event. This has rather unwanted side-effect of the event being disabled when there may be more space in the ring buffer. So, instead of TRUNCATE we need a different flag to indicate that the trace may have lost a few bytes (i.e from the point of generating the FILL event until the IRQ is consumed). Anyways, the userspace must use the size from RECORD_AUX headers to restrict the "trace" decoding. Using PARTIAL flag causes the perf tool to generate the following warning: Warning: AUX data had gaps in it XX times out of YY! Are you running a KVM guest in the background? which is pointlessly scary for a user. The other remaining options are : - COLLISION - Use by SPE to indicate samples collided - Add a new flag - Specifically for CoreSight, doesn't sound so good, if we can re-use something. Given that we don't already use the "COLLISION" flag, the above behavior can be notified using this flag for CoreSight. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: James Clark <james.clark@arm.com> Cc: Mike Leach <mike.leach@linaro.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Leo Yan <leo.yan@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- Changes since v2: - The perf tool patch for reporting collisions is queued. --- drivers/hwtracing/coresight/coresight-trbe.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)