Hi,
In cyclictest, by default "tracing_thresh" will be set to "tracelimit"
(given to cyclictest with option "-b tracelimit").
If the maximum latency of the tracer currently used is less than
"tracelimit", no trace will be recorded.
e.g:
./cyclictest -p 80 -t 1 -n -l 10000 -i 10000 -b 8000 -I -f
If the "irqsoff" maximum latency is less than 8000,
"/sys/kernel/debug/tracing/trace" will no contain valid "irqsoff"
trace.
This is not expected sometimes if e.g, the maximum latency of
cyclictest is caused by wakeup, but I want to see the irqsoff latency.
So I think it may be better to allow user set "tracing_thresh"
optionally, by adding a "--tracing_thresh=THRESH" option.
Here is a simple patch to show the idea:
Signed-off-by: yi.li@xxxxxxxxxx
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index ce4d911..c2f1c07 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -144,6 +144,7 @@ struct thread_stat {
static int shutdown;
static int tracelimit = 0;
+static int tracing_thresh = 0;
static int ftrace = 0;
static int kernelversion;
static int verbose = 0;
@@ -384,9 +385,11 @@ static void setup_tracer(void)
if (kernelversion == KV_26_CURR) {
char buffer[32];
int ret;
-
- sprintf(buffer, "%d", tracelimit);
- setkernvar("tracing_thresh", buffer);
+
+ if (tracing_thresh > 0 && tracing_thresh <= tracelimit) {
+ sprintf(buffer, "%d", tracing_thresh);
+ setkernvar("tracing_thresh", buffer);
+ }
/* ftrace_enabled is a sysctl variable */
fileprefix = procfileprefix;
@@ -766,6 +769,7 @@ static void display_help(int error)
" without -t default = 1\n"
"-T TRACE --tracer=TRACER set tracing function\n"
" configured tracers: %s\n"
+ "--tracing_thresh=THRESH set tracing_thresh of current
tracer to THRESH\n"
"-u --unbuffered force unbuffered output for live
processing\n"
"-v --verbose output values on stdout for statistics\n"
" format: n:c:v n=tasknum c=count
v=value in us\n"
@@ -896,6 +900,7 @@ static void process_options (int argc, char *argv[])
{"help", no_argument, NULL, '?'},
{"tracer", required_argument, NULL, 'T'},
{"traceopt", required_argument, NULL, 'O'},
+ {"tracing_thresh", required_argument, NULL, 1},
{"smp", no_argument, NULL, 'S'},
{NULL, 0, NULL, 0}
};
@@ -972,6 +977,7 @@ static void process_options (int argc, char *argv[])
use_nanosleep = MODE_CLOCK_NANOSLEEP;
break;
case '?': display_help(0); break;
+ case 1 : tracing_thresh = atoi(optarg); break;
}
}
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