cyclictest: Add long option --laptop to preserve battery power

Some people running cyclictest on laptops don't want to automatically
take advantage of the trick that prevents the power management to
transistion to high cstates, since it eats up their battery power.

Allow them to suppress this feature with --laptop

This will result in power latency results of course.

Feature-requested-by:  Joakim Hernberg <jhernberg@alchemy.lu>
Signed-off-by: John Kacur <jkacur@redhat.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index b45041e..a3e7b1d 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -186,6 +186,7 @@ static int use_fifo = 0;
 static pthread_t fifo_threadid;
 static int aligned = 0;
 static int offset = 0;
+static int laptop = 0;
 
 static pthread_cond_t refresh_on_max_cond = PTHREAD_COND_INITIALIZER;
 static pthread_mutex_t refresh_on_max_lock = PTHREAD_MUTEX_INITIALIZER;
@@ -235,6 +236,11 @@ static void set_latency_target(void)
 	struct stat s;
 	int err;
 
+	if (laptop) {
+		warn("not setting cpu_dma_latency to save battery power\n");
+		return;
+	}
+
 	errno = 0;
 	err = stat("/dev/cpu_dma_latency", &s);
 	if (err == -1) {
@@ -1020,6 +1026,9 @@ static void display_help(int error)
 	       "-i INTV  --interval=INTV   base interval of thread in us default=1000\n"
 	       "-I       --irqsoff         Irqsoff tracing (used with -b)\n"
 	       "-l LOOPS --loops=LOOPS     number of loops: default=0(endless)\n"
+	       "	 --laptop	   Save battery when running cyclictest\n"
+	       "			   This will give you poorer realtime results\n"
+	       "			   but will not drain your battery so quickly\n"
 	       "-m       --mlockall        lock current and future memory allocations\n"
 	       "-M       --refresh_on_max  delay updating the screen until a new max latency is hit\n"
 	       "-n       --nanosleep       use clock_nanosleep\n"
@@ -1183,7 +1192,7 @@ enum option_values {
 	OPT_QUIET, OPT_PRIOSPREAD, OPT_RELATIVE, OPT_RESOLUTION, OPT_SYSTEM,
 	OPT_SMP, OPT_THREADS, OPT_TRACER, OPT_UNBUFFERED, OPT_NUMA, OPT_VERBOSE,
 	OPT_WAKEUP, OPT_WAKEUPRT, OPT_DBGCYCLIC, OPT_POLICY, OPT_HELP, OPT_NUMOPTS,
-	OPT_ALIGNED,
+	OPT_ALIGNED, OPT_LAPTOP,
 };
 
 /* Process commandline options */
@@ -1216,6 +1225,7 @@ static void process_options (int argc, char *argv[], int max_cpus)
 			{"histofall",        required_argument, NULL, OPT_HISTOFALL },
 			{"interval",         required_argument, NULL, OPT_INTERVAL },
 			{"irqsoff",          no_argument,       NULL, OPT_IRQSOFF },
+			{"laptop",	     no_argument,	NULL, OPT_LAPTOP },
 			{"loops",            required_argument, NULL, OPT_LOOPS },
 			{"mlockall",         no_argument,       NULL, OPT_MLOCKALL },
 			{"refresh_on_max",   no_argument,       NULL, OPT_REFRESH },
@@ -1445,6 +1455,8 @@ static void process_options (int argc, char *argv[], int max_cpus)
 			handlepolicy(optarg); break;
 		case OPT_DBGCYCLIC:
 			ct_debug = 1; break;
+		case OPT_LAPTOP:
+			laptop = 1; break;
 		}
 	}