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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c')
-rw-r--r--kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c97
1 files changed, 97 insertions, 0 deletions
diff --git a/kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c b/kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c
new file mode 100644
index 000000000..81fdd425a
--- /dev/null
+++ b/kernel/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c
@@ -0,0 +1,97 @@
+/*
+ * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
+ *
+ * Tests if the control register is updated correctly
+ * at context switches
+ *
+ * Warning: this test will cause a very high load for a few seconds
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <inttypes.h>
+#include <wait.h>
+
+
+#include <sys/prctl.h>
+#include <linux/prctl.h>
+
+/* Get/set the process' ability to use the timestamp counter instruction */
+#ifndef PR_GET_TSC
+#define PR_GET_TSC 25
+#define PR_SET_TSC 26
+# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
+# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
+#endif
+
+static uint64_t rdtsc(void)
+{
+uint32_t lo, hi;
+/* We cannot use "=A", since this would use %rax on x86_64 */
+__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+return (uint64_t)hi << 32 | lo;
+}
+
+static void sigsegv_expect(int sig)
+{
+ /* */
+}
+
+static void segvtask(void)
+{
+ if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
+ {
+ perror("prctl");
+ exit(0);
+ }
+ signal(SIGSEGV, sigsegv_expect);
+ alarm(10);
+ rdtsc();
+ fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
+ exit(0);
+}
+
+
+static void sigsegv_fail(int sig)
+{
+ fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
+ exit(0);
+}
+
+static void rdtsctask(void)
+{
+ if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
+ {
+ perror("prctl");
+ exit(0);
+ }
+ signal(SIGSEGV, sigsegv_fail);
+ alarm(10);
+ for(;;) rdtsc();
+}
+
+
+int main(int argc, char **argv)
+{
+ int n_tasks = 100, i;
+
+ fprintf(stderr, "[No further output means we're allright]\n");
+
+ for (i=0; i<n_tasks; i++)
+ if (fork() == 0)
+ {
+ if (i & 1)
+ segvtask();
+ else
+ rdtsctask();
+ }
+
+ for (i=0; i<n_tasks; i++)
+ wait(NULL);
+
+ exit(0);
+}
+