On Mon, Mar 25, 2019 at 03:56:16PM -0600, Mathieu Poirier wrote:

This is the second revision of a patchset that adds support for CPU-wide
trace scenarios and as such, it is now possible to issue the following
commands:

	# perf record -e cs_etm/@20070000.etr/ -C 2,3 $COMMAND
	# perf record -e cs_etm/@20070000.etr/ -a $COMMAND

The solution is designed to work for both 1:1 and N:1 source/sink
topologies, though the former hasn't been tested for lack of access to HW.

Most of the changes revolve around allowing more than one event to use
a sink when operated from perf.  More specifically the first event to
use a sink switches it on while the last one is tasked to aggregate traces
and switching off the device.

This is the kernel part of the solution, with the user space portion to be
released in a later set.  All patches (user and kernel) have been rebased
on v5.1-rc2 and are hosted here[1].  Everything has been tested on Juno and
410c dragonboard platforms.

FWIW, gave the testing on my Hikey620 board and these patches also work
well with below commands:

  # perf record -e cs_etm/@f6402000.etf/ -a uname
  # perf record -e cs_etm/@f6402000.etf/ -C 0,4 uname

  # perf record -e cs_etm/@f6404000.etr/ -a uname
  # perf record -e cs_etm/@f6404000.etr/ -C 1,2,7 uname

P.s. just note here and this is off topic to this patch set, the
'perf report' command took below time for decoding ~4MB CoreSight trace
data on my Hikey board, seems we can take a look for decoding speed
optimization later:

  # time perf report  --vmlinux /mnt/linux-kernel/linux-next/vmlinux
  real    2m11.153s
  user    1m47.979s
  sys     0m0.204s

Thanks,
Leo Yan

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