| Message ID | 20210723124611.3828908-10-suzuki.poulose@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: TRBE and Self-Hosted trace fixes | expand |
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>
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; }
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. 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. 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(-)