From 13c2688c4e52aeff1874a1e23abff3db3488f458 Mon Sep 17 00:00:00 2001
From: CSRG <csrg@ucbvax.Berkeley.EDU>
Date: Mon, 7 Jun 1993 21:24:44 -0800
Subject: [PATCH] BSD 4_4_Lite2 development Work on file
 usr/src/sys/tests/benchmarks/csw.c

Synthesized-from: CSRG/cd3/4.4BSD-Lite2
---
 usr/src/sys/tests/benchmarks/csw.c | 54 ++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 usr/src/sys/tests/benchmarks/csw.c

diff --git a/usr/src/sys/tests/benchmarks/csw.c b/usr/src/sys/tests/benchmarks/csw.c
new file mode 100644
index 0000000000..8186082d00
--- /dev/null
+++ b/usr/src/sys/tests/benchmarks/csw.c
@@ -0,0 +1,54 @@
+/*
+ * Context switching benchmark.
+ *
+ * Force system to context switch 2*nsigs
+ * times by forking and exchanging signals.
+ * To calculate system overhead for a context
+ * switch, the signocsw program must be run
+ * with nsigs.  Overhead is then estimated by
+ *	t1 = time csw <n>
+ *	t2 = time signocsw <n>
+ *	overhead = t1 - 2 * t2;
+ */
+#include <signal.h>
+
+void	sigsub();
+int	otherpid;
+int	nsigs;
+
+main(argc, argv)
+	char *argv[];
+{
+	int pid;
+
+	if (argc < 2) {
+		printf("usage: %s nsignals\n", argv[0]);
+		exit(1);
+	}
+	nsigs = atoi(argv[1]);
+	signal(SIGALRM, sigsub);
+	otherpid = getpid();
+	pid = fork();
+	if (pid != 0) {
+		otherpid = pid;
+		kill(otherpid, SIGALRM);
+	}
+	for (;;)
+		sigpause(0);
+}
+
+void
+sigsub()
+{
+	static mustreset = 1;
+	void (*osig)();
+
+	if (mustreset) {
+		osig = signal(SIGALRM, sigsub);
+		if (osig == sigsub)
+			mustreset = 0;
+	}
+	kill(otherpid, SIGALRM);
+	if (--nsigs <= 0)
+		exit(0);
+}
-- 
2.20.1