Messages in this thread | | | Subject | Re: [PATCH v2 26/27] coresight: perf: Remove reset_buffer call back for sinks | From | Suzuki K Poulose <> | Date | Fri, 11 May 2018 17:35:19 +0100 |
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On 08/05/18 20:42, Mathieu Poirier wrote: > On Tue, May 01, 2018 at 10:10:56AM +0100, Suzuki K Poulose wrote: >> Right now we issue an update_buffer() and reset_buffer() call backs >> in succession when we stop tracing an event. The update_buffer is >> supposed to check the status of the buffer and make sure the ring buffer >> is updated with the trace data. And we store information about the >> size of the data collected only to be consumed by the reset_buffer >> callback which always follows the update_buffer. This was originally >> designed for handling future IPs which could trigger a buffer overflow >> interrupt. This patch gets rid of the reset_buffer callback altogether >> and performs the actions in update_buffer, making it return the size >> collected. We can always add the support for handling the overflow >> interrupt case later. >> >> This removes some not-so pretty hack (storing the new head in the >> size field for snapshot mode) and cleans it up a little bit. > > IPs with an overflow interrupts will be arriving shortly, so it is not like the > future is uncertain - they are coming. Right now the logic is there - I don't > see a real need to consolidate things only to split it again in the near future. > > I agree the part about overloading buf->data_size with the head of the ring > buffer when operating in snapshot mode isn't pretty (though well documented). > If anything that can be improve, i.e add a buf->head and things will be clear. > Once again this could be part of another patchset. >
Mathieu,
I am not sure how was this supposed to be used in conjunction with the overflow handling. Please could you help me here ? I might be able to retain the callback and possibly improve it with the changes for etr_buf infrastructure.
Cheers Suzuki
>> >> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >> --- >> drivers/hwtracing/coresight/coresight-etb10.c | 56 +++++------------------ >> drivers/hwtracing/coresight/coresight-etm-perf.c | 9 +--- >> drivers/hwtracing/coresight/coresight-tmc-etf.c | 58 +++++------------------- >> include/linux/coresight.h | 5 +- >> 4 files changed, 26 insertions(+), 102 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c >> index d9c2f87..b13712a 100644 >> --- a/drivers/hwtracing/coresight/coresight-etb10.c >> +++ b/drivers/hwtracing/coresight/coresight-etb10.c >> @@ -322,37 +322,7 @@ static int etb_set_buffer(struct coresight_device *csdev, >> return ret; >> } >> >> -static unsigned long etb_reset_buffer(struct coresight_device *csdev, >> - struct perf_output_handle *handle, >> - void *sink_config) >> -{ >> - unsigned long size = 0; >> - struct cs_buffers *buf = sink_config; >> - >> - if (buf) { >> - /* >> - * In snapshot mode ->data_size holds the new address of the >> - * ring buffer's head. The size itself is the whole address >> - * range since we want the latest information. >> - */ >> - if (buf->snapshot) >> - handle->head = local_xchg(&buf->data_size, >> - buf->nr_pages << PAGE_SHIFT); >> - >> - /* >> - * Tell the tracer PMU how much we got in this run and if >> - * something went wrong along the way. Nobody else can use >> - * this cs_buffers instance until we are done. As such >> - * resetting parameters here and squaring off with the ring >> - * buffer API in the tracer PMU is fine. >> - */ >> - size = local_xchg(&buf->data_size, 0); >> - } >> - >> - return size; >> -} >> - >> -static void etb_update_buffer(struct coresight_device *csdev, >> +static unsigned long etb_update_buffer(struct coresight_device *csdev, >> struct perf_output_handle *handle, >> void *sink_config) >> { >> @@ -361,13 +331,13 @@ static void etb_update_buffer(struct coresight_device *csdev, >> u8 *buf_ptr; >> const u32 *barrier; >> u32 read_ptr, write_ptr, capacity; >> - u32 status, read_data, to_read; >> - unsigned long offset; >> + u32 status, read_data; >> + unsigned long offset, to_read; >> struct cs_buffers *buf = sink_config; >> struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); >> >> if (!buf) >> - return; >> + return 0; >> >> capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS; >> >> @@ -472,18 +442,17 @@ static void etb_update_buffer(struct coresight_device *csdev, >> writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER); >> >> /* >> - * In snapshot mode all we have to do is communicate to >> - * perf_aux_output_end() the address of the current head. In full >> - * trace mode the same function expects a size to move rb->aux_head >> - * forward. >> + * In snapshot mode we have to update the handle->head to point >> + * to the new location. >> */ >> - if (buf->snapshot) >> - local_set(&buf->data_size, (cur * PAGE_SIZE) + offset); >> - else >> - local_add(to_read, &buf->data_size); >> - >> + if (buf->snapshot) { >> + handle->head = (cur * PAGE_SIZE) + offset; >> + to_read = buf->nr_pages << PAGE_SHIFT; >> + } >> etb_enable_hw(drvdata); >> CS_LOCK(drvdata->base); >> + >> + return to_read; >> } >> >> static const struct coresight_ops_sink etb_sink_ops = { >> @@ -492,7 +461,6 @@ static const struct coresight_ops_sink etb_sink_ops = { >> .alloc_buffer = etb_alloc_buffer, >> .free_buffer = etb_free_buffer, >> .set_buffer = etb_set_buffer, >> - .reset_buffer = etb_reset_buffer, >> .update_buffer = etb_update_buffer, >> }; >> >> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c >> index 4e5ed65..5096def 100644 >> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c >> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c >> @@ -342,15 +342,8 @@ static void etm_event_stop(struct perf_event *event, int mode) >> if (!sink_ops(sink)->update_buffer) >> return; >> >> - sink_ops(sink)->update_buffer(sink, handle, >> + size = sink_ops(sink)->update_buffer(sink, handle, >> event_data->snk_config); >> - >> - if (!sink_ops(sink)->reset_buffer) >> - return; >> - >> - size = sink_ops(sink)->reset_buffer(sink, handle, >> - event_data->snk_config); >> - >> perf_aux_output_end(handle, size); >> } >> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c >> index 0a32734..75ef5c4 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c >> @@ -360,36 +360,7 @@ static int tmc_set_etf_buffer(struct coresight_device *csdev, >> return ret; >> } >> >> -static unsigned long tmc_reset_etf_buffer(struct coresight_device *csdev, >> - struct perf_output_handle *handle, >> - void *sink_config) >> -{ >> - long size = 0; >> - struct cs_buffers *buf = sink_config; >> - >> - if (buf) { >> - /* >> - * In snapshot mode ->data_size holds the new address of the >> - * ring buffer's head. The size itself is the whole address >> - * range since we want the latest information. >> - */ >> - if (buf->snapshot) >> - handle->head = local_xchg(&buf->data_size, >> - buf->nr_pages << PAGE_SHIFT); >> - /* >> - * Tell the tracer PMU how much we got in this run and if >> - * something went wrong along the way. Nobody else can use >> - * this cs_buffers instance until we are done. As such >> - * resetting parameters here and squaring off with the ring >> - * buffer API in the tracer PMU is fine. >> - */ >> - size = local_xchg(&buf->data_size, 0); >> - } >> - >> - return size; >> -} >> - >> -static void tmc_update_etf_buffer(struct coresight_device *csdev, >> +static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev, >> struct perf_output_handle *handle, >> void *sink_config) >> { >> @@ -398,17 +369,17 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev, >> const u32 *barrier; >> u32 *buf_ptr; >> u64 read_ptr, write_ptr; >> - u32 status, to_read; >> - unsigned long offset; >> + u32 status; >> + unsigned long offset, to_read; >> struct cs_buffers *buf = sink_config; >> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); >> >> if (!buf) >> - return; >> + return 0; >> >> /* This shouldn't happen */ >> if (WARN_ON_ONCE(drvdata->mode != CS_MODE_PERF)) >> - return; >> + return 0; >> >> CS_UNLOCK(drvdata->base); >> >> @@ -497,18 +468,14 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev, >> } >> } >> >> - /* >> - * In snapshot mode all we have to do is communicate to >> - * perf_aux_output_end() the address of the current head. In full >> - * trace mode the same function expects a size to move rb->aux_head >> - * forward. >> - */ >> - if (buf->snapshot) >> - local_set(&buf->data_size, (cur * PAGE_SIZE) + offset); >> - else >> - local_add(to_read, &buf->data_size); >> - >> + /* In snapshot mode we have to update the head */ >> + if (buf->snapshot) { >> + handle->head = (cur * PAGE_SIZE) + offset; >> + to_read = buf->nr_pages << PAGE_SHIFT; >> + } >> CS_LOCK(drvdata->base); >> + >> + return to_read; >> } >> >> static const struct coresight_ops_sink tmc_etf_sink_ops = { >> @@ -517,7 +484,6 @@ static const struct coresight_ops_sink tmc_etf_sink_ops = { >> .alloc_buffer = tmc_alloc_etf_buffer, >> .free_buffer = tmc_free_etf_buffer, >> .set_buffer = tmc_set_etf_buffer, >> - .reset_buffer = tmc_reset_etf_buffer, >> .update_buffer = tmc_update_etf_buffer, >> }; >> >> diff --git a/include/linux/coresight.h b/include/linux/coresight.h >> index c0e1568..41b3729 100644 >> --- a/include/linux/coresight.h >> +++ b/include/linux/coresight.h >> @@ -212,10 +212,7 @@ struct coresight_ops_sink { >> int (*set_buffer)(struct coresight_device *csdev, >> struct perf_output_handle *handle, >> void *sink_config); >> - unsigned long (*reset_buffer)(struct coresight_device *csdev, >> - struct perf_output_handle *handle, >> - void *sink_config); >> - void (*update_buffer)(struct coresight_device *csdev, >> + unsigned long (*update_buffer)(struct coresight_device *csdev, >> struct perf_output_handle *handle, >> void *sink_config); >> }; >> -- >> 2.7.4 >>
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