Messages in this thread | | | Subject | Re: [PATCH 13/17] coresight etr: Do not clean ETR trace buffer | From | Suzuki K Poulose <> | Date | Tue, 7 Nov 2017 10:37:22 +0000 |
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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
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