On 03/11/17 20:17, Mathieu Poirier wrote:
On 3 November 2017 at 04:10, Suzuki K Poulose Suzuki.Poulose@arm.com wrote:
On 02/11/17 20:36, Mathieu Poirier wrote:
On Thu, Oct 19, 2017 at 06:15:49PM +0100, Suzuki K Poulose wrote:
We zero out the entire trace buffer used for ETR before it is enabled, for helping with debugging. Since we could be restoring a session in perf mode, this could destroy the data.
I'm not sure to follow you with "... restoring a session in perf mode ...". When operating from the perf interface all the memory allocated for a session is cleanup after, there is no re-using of memory as in sysFS.
We could directly use the perf ring buffer for the ETR. In that case, the perf ring buffer could contain trace data collected from the previous "schedule" which the userspace hasn't collected yet. So, doing a memset here would destroy that data.
I originally thought your comment was about re-using the memory from a previous trace session, hence the confusion. Please rework your changelog to include this clarification as I am sure other people can be mislead.
Sure, will do.
Thanks Suzuki