Thank you Leo, this is really valuable!
I'm going to update my kernel version to the latest one - hopefully I'll manage to do this as soon as possible

As I'm trying different configurations, I've got a very interesting result:

$ taskset -c 0 perf record --per-thread -e cs_etm/sinkid=0xa6509eae/u  ~/afdo/coremark/coremark/coremark.exe  0x3415 0x3415 0x66 0 7 1 2000  > run2.log
[ perf record: Woken up 28 times to write data ]
Warning:
AUX data lost 25 times out of 27!

[ perf record: Captured and wrote 3.323 MB perf.data ]

While instead, when NOT pinning the program to a specific core

$ perf record --per-thread -e cs_etm/sinkid=0xa6509eae/u  ~/afdo/coremark/coremark/coremark.exe  0x3415 0x3415 0x66 0 7 1 2000  > run2.log
[ perf record: Woken up 4 times to write data ]
Warning:
AUX data lost 4 times out of 4!

[ perf record: Captured and wrote 0.502 MB perf.data ]

While the information lost rate is still high, the `time` AUX data has been lost is very different: 27 vs 4
Also the reported perf.data file is way bigger when pinning the task to a specific core.

Interestingly enough, when instead tracing a short-lived program such as `ls`, there is no difference in the perf.data reported.

Is anybody aware of any specific part in the code base whose behavior may change according to the traced program being rescheduled to another core?
Any idea/suggestion is highly appreciated

Thanks,
Andrea

From: Leo Yan <leo.yan@linaro.org>
Sent: 05 March 2020 01:55
To: Andrea Brunato <Andrea.Brunato@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>; Mathieu Poirier <mathieu.poirier@linaro.org>; guermazi.zied@gmail.com <guermazi.zied@gmail.com>; coresight@lists.linaro.org <coresight@lists.linaro.org>
Subject: Re: perf record cs_etm: data lost
 
Hi Andrea,

On Wed, Mar 04, 2020 at 03:45:59PM +0000, Andrea Brunato wrote:
> Thank you Mike - I'm getting a way better understanding of the whole system.
>
> Sorry for sharing a wrong command, unfortunately on 5.5.0-rc7 I see the same error persisting when running:
>
> $ perf record --per-thread -e cs_etm/@tmc_etr0/u  -- ls
> failed to set sink "" on event cs_etm/@tmc_etr0/u with 21 (Is a directory)
>
> I'm using perf built as an Arm binary against the same kernel source code while linked against openCSD.

Just want to remind, please check if these two patches [1][2] have been
merged into your local code base, otherwise, before we found the
regression for inputting sink name in perf command.

Thanks,
Leo

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e884602b57c07fae54ff357e4b996b2053b47c1e
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3220fb8d5e59d7a9b59d02965d4209aef7691e9f
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.