Hi Peter,

On Fri, 2021-07-09 at 14:39 -0400, Peter Xu wrote:

On Fri, Jul 09, 2021 at 05:54:14PM +0200, Nicolas Saenz Julienne wrote:

quoted

After a long tracing session it's sometimes hard to find the moment
oslat started. So leave a message in the trace buffer just before the
main thread starts.

Signed-off-by: Nicolas Saenz Julienne <redacted>
---
 src/oslat/oslat.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
index d35be57..20bf02b 100644
--- a/src/oslat/oslat.c
+++ b/src/oslat/oslat.c

@@ -400,6 +400,10 @@ static void *thread_main(void *arg)
 	while (g.n_threads_running != g.n_threads)
 		relax();
 
+	if (!g.preheat)
+		tracemark(false, "%s: Starting thread on CPU %d.\n",
+			  g.app_name, t->core_i);
+
 	frc(&t->frc_start);
 	doit(t);
 	frc(&t->frc_stop);

-- 
2.31.1

Not sure how it would help.. but no objection either. :)

For example, I tend to enable all trace points on Isolated CPUs. It's
manageable, since once oslat runs you shouldn't be getting much action. But you
get 10s/100s MBs of noise generated while oslat is being initialized. This
makes finding the beginning of the test very annoying and time consuming.

Acked-by: Peter Xu <peterx@redhat.com>

Thanks!