Messages in this thread |  | | Subject | Re: [PATCH v2 09/10] coresight: trbe: End the AUX handle on truncation | From | Anshuman Khandual <> | Date | Fri, 30 Jul 2021 11:24:44 +0530 |
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On 7/23/21 6:16 PM, Suzuki K Poulose wrote: > When we detect that there isn't enough space left to start > a meaningful session, we disable the TRBE, marking the buffer > as TRUNCATED. But we delay the notification to the perf layer > by perf_aux_output_end() until the event is scheduled out.
via the CoreSight PMU layer's stop event ?
> This will cause significant black outs in the trace. Now that > the CoreSight PMU layer can handle a closed "AUX" handle > properly, we can close the handle as soon as we detect the > case, allowing the userspace to collect and re-enable the > event. > > Also, while in the IRQ handler, move the irq_work_run() after > we have updated the handle, to make sure the "TRUNCATED" flag > causes the event to be disabled as soon as possible.
Makes sense.
Minor nit. Commit message here should be reformatted to be expanded upto 75 character width.
> > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Leo Yan <leo.yan@linaro.org> > Cc: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: Will Deacon <will@kernel.org> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > drivers/hwtracing/coresight/coresight-trbe.c | 25 ++++++++++++-------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 6d6aad171c72..e7567727e8fc 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -134,6 +134,7 @@ static void trbe_stop_and_truncate_event(struct perf_output_handle *handle) > trbe_drain_and_disable_local(); > perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED | > PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW); > + perf_aux_output_end(handle, 0); > *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL; > } > > @@ -699,7 +700,7 @@ static void trbe_handle_spurious(struct perf_output_handle *handle) > isb(); > } > > -static void trbe_handle_overflow(struct perf_output_handle *handle) > +static int trbe_handle_overflow(struct perf_output_handle *handle) > { > struct perf_event *event = handle->event; > struct trbe_buf *buf = etm_perf_sink_config(handle); > @@ -728,10 +729,10 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > */ > trbe_drain_and_disable_local(); > *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL; > - return; > + return -EINVAL; > } > > - __arm_trbe_enable(buf, handle); > + return __arm_trbe_enable(buf, handle); > } > > static bool is_perf_trbe(struct perf_output_handle *handle) > @@ -762,6 +763,7 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) > struct perf_output_handle *handle = *handle_ptr; > enum trbe_fault_action act; > u64 status; > + bool truncated = false; > > /* Reads to TRBSR_EL1 is fine when TRBE is active */ > status = read_sysreg_s(SYS_TRBSR_EL1); > @@ -786,24 +788,27 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) > if (!is_perf_trbe(handle)) > return IRQ_NONE; > > - /* > - * Ensure perf callbacks have completed, which may disable > - * the trace buffer in response to a TRUNCATION flag. > - */ > - irq_work_run(); > - > act = trbe_get_fault_act(status); > switch (act) { > case TRBE_FAULT_ACT_WRAP: > - trbe_handle_overflow(handle); > + truncated = !!trbe_handle_overflow(handle); > break; > case TRBE_FAULT_ACT_SPURIOUS: > trbe_handle_spurious(handle); > break; > case TRBE_FAULT_ACT_FATAL: > trbe_stop_and_truncate_event(handle); > + truncated = true; > break; > } > + > + /* > + * If the buffer was truncated, ensure perf callbacks > + * have completed, which will disable the event. > + */ > + if (truncated) > + irq_work_run(); > + > return IRQ_HANDLED; > } > >
LGTM.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
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