* cyclictest: write tracemark if latency above spike value
@ 2023-03-01 19:55 Marcelo Tosatti
0 siblings, 0 replies; only message in thread
From: Marcelo Tosatti @ 2023-03-01 19:55 UTC (permalink / raw)
To: John Kacur, linux-rt-users
It is useful to have the following ranges:
Value Behaviour
> break_lat -> write tracemark entry, quit cyclictest.
[spike, break_lat] -> write tracemark entry, continue execution.
< spike -> no tracemark entry, continue execution.
So one can know which events are causing "close to break value"
(and their causes).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 82759d1..22eab05 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -1698,6 +1698,9 @@ static void trigger_update(struct thread_param *par, int diff, int64_t ts)
}
spikes++;
pthread_mutex_unlock(&trigger_lock);
+ if (trace_marker && diff > trigger) {
+ tracemark_nostop("hit latency trigger (%d > %d)", diff, trigger);
+ }
}
/* Running status shared memory open */
@@ -1892,7 +1895,7 @@ int main(int argc, char **argv)
/* use the /dev/cpu_dma_latency trick if it's there */
set_latency_target();
- if (tracelimit && trace_marker)
+ if ((tracelimit && trace_marker) || (trigger && trace_marker))
enable_trace_mark();
if (check_timer())
diff --git a/src/include/rt-utils.h b/src/include/rt-utils.h
index f6b3fed..85a459f 100644
--- a/src/include/rt-utils.h
+++ b/src/include/rt-utils.h
@@ -32,6 +32,7 @@ int parse_mem_string(char *str, uint64_t *val);
void enable_trace_mark(void);
void tracemark(char *fmt, ...) __attribute__((format(printf, 1, 2)));
+void tracemark_nostop(char *fmt, ...) __attribute__((format(printf, 1, 2)));
void disable_trace_mark(void);
#define MSEC_PER_SEC 1000
diff --git a/src/lib/rt-utils.c b/src/lib/rt-utils.c
index 6c0235d..daa8bb8 100644
--- a/src/lib/rt-utils.c
+++ b/src/lib/rt-utils.c
@@ -458,7 +458,7 @@ static void debugfs_prepare(void)
"debug fs not mounted");
}
-void tracemark(char *fmt, ...)
+void tracemark_nostop(char *fmt, ...)
{
va_list ap;
int len;
@@ -474,6 +474,21 @@ void tracemark(char *fmt, ...)
/* write the tracemark message */
write(tracemark_fd, tracebuf, len);
+}
+
+void tracemark(char *fmt, ...)
+{
+ va_list ap;
+ int len;
+
+ /* bail out if we're not tracing */
+ /* or if the kernel doesn't support trace_mark */
+ if (tracemark_fd < 0 || trace_fd < 0)
+ return;
+
+ va_start(ap, fmt);
+ len = vsnprintf(tracebuf, TRACEBUFSIZ, fmt, ap);
+ va_end(ap);
/* now stop any trace */
write(trace_fd, "0\n", 2);
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2023-03-01 19:55 cyclictest: write tracemark if latency above spike value Marcelo Tosatti
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