[patch v4] rt-tests: add task isolation activation to cyclictest/oslat

[Marcelo Tosatti <mtosatti@redhat.com>]

Check whether task isolation is configured, right before the latency
sensitive loop, and if so, activate it.

Use chisol util-linux tool to configure task isolation externally.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 2187d98..2e13046 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -515,10 +515,13 @@ static void *timerthread(void *param)
 	struct itimerval itimer;
 	struct itimerspec tspec;
 	struct thread_stat *stat = par->stats;
-	int stopped = 0;
+	int stopped = 0, ret = 0;
 	cpu_set_t mask;
 	pthread_t thread;
 	unsigned long smi_now, smi_old = 0;
+#ifdef PR_ISOL_CFG_GET
+	unsigned long long isol_mask = 0;
+#endif
 
 	memset(&stop, 0, sizeof(stop));
 
@@ -623,11 +626,20 @@ static void *timerthread(void *param)
 
 	stat->threadstarted++;
 
+#ifdef PR_ISOL_CFG_GET
+	ret = prctl(PR_ISOL_CFG_GET, I_CFG_FEAT, 0, &isol_mask, 0);
+	if (ret != -1 && isol_mask != 0) {
+		ret = prctl(PR_ISOL_ACTIVATE_SET, &isol_mask, 0, 0);
+		if (ret == -1)
+			fatal("prctl PR_ISOL_ACTIVATE_SET");
+	}
+#endif
+
 	while (!shutdown) {
 
 		uint64_t diff;
 		unsigned long diff_smi = 0;
-		int sigs, ret;
+		int sigs;
 
 		/* Wait for next period */
 		switch (par->mode) {
@@ -775,6 +787,14 @@ static void *timerthread(void *param)
 	}
 
 out:
+#ifdef PR_ISOL_ACTIVATE_SET
+	if (isol_mask != 0) {
+		ret = prctl(PR_ISOL_ACTIVATE_SET, &isol_mask, 0, 0);
+		if (ret == -1)
+			fatal("prctl PR_ISOL_ACTIVATE_SET");
+	}
+#endif
+
 	if (refresh_on_max) {
 		pthread_mutex_lock(&refresh_on_max_lock);
 		/* We could reach here with both shutdown and allstopped unset (0).
diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
index 50ddc81..2105af0 100644
--- a/src/oslat/oslat.c
+++ b/src/oslat/oslat.c
@@ -31,6 +31,7 @@
 #include <limits.h>
 #include <stdbool.h>
 
+#include <linux/prctl.h>
 #include <sys/prctl.h>
 #include <sys/stat.h>
 #include <sys/sysinfo.h>
@@ -383,9 +384,20 @@ static void insert_bucket(struct thread *t, stamp_t value)
 
 static void doit(struct thread *t)
 {
+#ifdef PR_ISOL_CFG_GET
+	int ret;
+	unsigned long long isol_mask;
+#endif
+
 	stamp_t ts1, ts2;
 	workload_fn workload_fn = g.workload->w_fn;
 
+#ifdef PR_ISOL_CFG_GET
+	ret = prctl(PR_ISOL_CFG_GET, I_CFG_FEAT, 0, &isol_mask, 0);
+	if (ret != -1 && isol_mask != 0)
+		TEST0(prctl(PR_ISOL_ACTIVATE_SET, &isol_mask, 0, 0, 0));
+#endif
+
 	frc(&ts2);
 	do {
 		workload_fn(t->dst_buf, t->src_buf, g.workload_mem_size);
@@ -393,6 +405,13 @@ static void doit(struct thread *t)
 		insert_bucket(t, ts1 - ts2);
 		ts2 = ts1;
 	} while (g.cmd == GO);
+
+#ifdef PR_ISOL_CFG_GET
+	if (isol_mask != 0) {
+		isol_mask = 0;
+		TEST0(prctl(PR_ISOL_ACTIVATE_SET, &isol_mask, 0, 0, 0));
+	}
+#endif
 }
 
 static int set_fifo_prio(int prio)