Hi Mathieu,
On 01/05/2019 18:50, Mathieu Poirier wrote:
In snapshot mode the buffer used by the sink devices need to be equal to the ring buffer size in order for the user space mechanic to work properly.
The patch as such looks good to me. However I don't understand the need for it for ETB and ETF. We can't use the AUX buf directly anyway for these devices. We could always pretend that there was no overflow and simply copy it to the AUX buf. The decoder would know the end of trace packets. What am I missing here ?
Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org
drivers/hwtracing/coresight/coresight-etb10.c | 23 +++++++++++++++++++ .../hwtracing/coresight/coresight-tmc-etf.c | 20 ++++++++++++++++ .../hwtracing/coresight/coresight-tmc-etr.c | 8 +++++-- 3 files changed, 49 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index 4ee4c80a4354..0764647b92bc 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -374,7 +374,30 @@ static void *etb_alloc_buffer(struct coresight_device *csdev, int nr_pages, bool overwrite) { int node, cpu = event->cpu;
- u32 capacity; struct cs_buffers *buf;
- struct etb_drvdata *drvdata;
- /*
* In snapsot mode the size of the perf ring buffer needs to be equal* to the size of the device's internal memory if we want to reuse the* generic AUX buffer management mechanic.** For example (assuming 4096 byte page size):** # cat /sys/bus/coresight/devices/20010000.etb/mgmt/rdp* 0x2000* # perf record -e cs_etm/@20010000.etf/ -S -m,8 --per-thread $APP**/
If at all we need to do this, Is there a way to force the perf to use the appropriate size for AUX buf depending on the sink ? I would prefer that instead of finding this magic number and calculating it based on the page_size. If we could not do that easily, it may be a good idea to expose something like, "buffer_pages" under sysfs to help the user a bit.
Suzuki