perf tools: Add 'ping' control command
Add a control 'ping' command to detect if perf is up and its control
interface is operational.
It will be used in following daemon patches to synchronize with record
session - when control interface is up and running, we know that perf
record is monitoring and ready to receive signals.
Example session:
terminal 1:
# mkfifo control ack
# perf record --control=fifo:control,ack
terminal 2:
# echo ping > control
# cat ack
ack
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201226232038.390883-5-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
5 files changed