Re: [PATCH v3 01/17] tools/rv: Do not skip idle in trace

On Wed, 2025-07-16 at 13:50 +0200, Peter Zijlstra wrote:

On Tue, Jul 15, 2025 at 09:14:18AM +0200, Gabriele Monaco wrote:

quoted

Currently, the userspace RV tool skips trace events triggered by
the RV
tool itself, this can be changed by passing the parameter -s, which
sets
the variable config_my_pid to 0 (instead of the tool's PID).
The current condition for per-task monitors (config_has_id) does
not
check that config_my_pid isn't 0 to skip. In case we pass -s, we
show
events triggered by RV but don't show those triggered by idle (PID
0).

Fix the condition to account this scenario.

The distinction between !my_pid and has_id is that you can in fact
trace
pid-0 if you want?

Yes pretty much, no flag is meant to skip events from pid-0.


has_id is used to distinguish between per-cpu/global monitors (they
don't have id) and per-task monitors (the id is the pid).

The case with !has_id is correctly checking for both my_pid != 0 while
skipping events associated to my_pid (rv thread's PID).

In the other case we end up with:
* -s skipping events generated by the tool (correct)
* omitting -s skips events generated by pid-0 (undesired)

quoted

Fixes: 6d60f89691fc ("tools/rv: Add in-kernel monitor interface")
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
 tools/verification/rv/src/in_kernel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/verification/rv/src/in_kernel.c

b/tools/verification/rv/src/in_kernel.c
index c0dcee795c0de..72b03bae021cd 100644

--- a/tools/verification/rv/src/in_kernel.c
+++ b/tools/verification/rv/src/in_kernel.c

@@ -429,7 +429,7 @@ ikm_event_handler(struct trace_seq *s, struct

tep_record *record,
 
 	tep_get_common_field_val(s, trace_event, "common_pid",
record, &pid, 1);
 
-	if (config_has_id && (config_my_pid == id))
+	if (config_my_pid && config_has_id && (config_my_pid ==
id))
 		return 0;
 	else if (config_my_pid && (config_my_pid == pid))
 		return 0;
-- 
2.50.1