[RFC] [PATCH] [2.5.35] Run Queue Statistics

[Lev Makhlis <mlev@despammed.com>]

This patch adds two counters, runque and runocc, similar to those
in traditional UNIX systems, to measure the run queue occupancy.
Every second, 'runque' is incremented by the run queue size, and
'runocc' is incremented by one if the run queue is not empty.

I am not comfortable about putting the calculation in the same function
as the load average calculation, but I didn't want to call
count_active_tasks() twice. Comments are welcome.

Lev

--------------------------------------------------------------------------
diff -urN linux-2.5.35.orig/fs/proc/proc_misc.c 
linux-2.5.35/fs/proc/proc_misc.c
--- linux-2.5.35.orig/fs/proc/proc_misc.c	Sun Sep 15 22:18:21 2002
+++ linux-2.5.35/fs/proc/proc_misc.c	Mon Sep 16 13:36:14 2002
@@ -386,7 +386,8 @@
 		"allocstall %u\n"
 		"ctxt %lu\n"
 		"btime %lu\n"
-		"processes %lu\n",
+		"processes %lu\n"
+		"runque %u %u\n",
 		kstat.pgalloc,
 		kstat.pgfree,
 		kstat.pgactivate,
@@ -399,7 +400,9 @@
 		kstat.allocstall,
 		nr_context_switches(),
 		xtime.tv_sec - jif / HZ,
-		total_forks);
+		total_forks,
+		kstat.runque,
+		kstat.runocc);
 
 	return proc_calc_metrics(page, start, off, count, eof, len);
 }
diff -urN linux-2.5.35.orig/include/linux/kernel_stat.h 
linux-2.5.35/include/linux/kernel_stat.h
--- linux-2.5.35.orig/include/linux/kernel_stat.h	Sun Sep 15 22:18:27 2002
+++ linux-2.5.35/include/linux/kernel_stat.h	Mon Sep 16 13:35:30 2002
@@ -31,6 +31,7 @@
 	unsigned int pgfault, pgmajfault;
 	unsigned int pgscan, pgsteal;
 	unsigned int pageoutrun, allocstall;
+	unsigned int runque, runocc;
 #if !defined(CONFIG_ARCH_S390)
 	unsigned int irqs[NR_CPUS][NR_IRQS];
 #endif
diff -urN linux-2.5.35.orig/kernel/timer.c linux-2.5.35/kernel/timer.c
--- linux-2.5.35.orig/kernel/timer.c	Sun Sep 15 22:18:24 2002
+++ linux-2.5.35/kernel/timer.c	Mon Sep 16 13:36:31 2002
@@ -592,11 +592,11 @@
 }
 
 /*
- * Nr of active tasks - counted in fixed-point numbers
+ * Nr of active tasks
  */
 static unsigned long count_active_tasks(void)
 {
-	return (nr_running() + nr_uninterruptible()) * FIXED_1;
+	return nr_running() + nr_uninterruptible();
 }
 
 /*
@@ -615,16 +615,29 @@
  */
 static inline void calc_load(unsigned long ticks)
 {
-	unsigned long active_tasks; /* fixed-point */
-	static int count = LOAD_FREQ;
+	unsigned long active_tasks;
+	unsigned long fp_active_tasks; /* fixed-point */
+	static int load_count = LOAD_FREQ;
+	static int runq_count = HZ;
 
-	count -= ticks;
-	if (count < 0) {
-		count += LOAD_FREQ;
+	load_count -= ticks;
+	runq_count -= ticks;
+	if (load_count < 0 || runq_count < 0) {
 		active_tasks = count_active_tasks();
-		CALC_LOAD(avenrun[0], EXP_1, active_tasks);
-		CALC_LOAD(avenrun[1], EXP_5, active_tasks);
-		CALC_LOAD(avenrun[2], EXP_15, active_tasks);
+		if (runq_count < 0) {
+			runq_count += HZ;
+			if (active_tasks) {
+				kstat.runque += active_tasks;
+				kstat.runocc ++;
+			}
+		}
+		if (load_count < 0) {
+			load_count += LOAD_FREQ;
+			fp_active_tasks = active_tasks * FIXED_1;
+			CALC_LOAD(avenrun[0], EXP_1, fp_active_tasks);
+			CALC_LOAD(avenrun[1], EXP_5, fp_active_tasks);
+			CALC_LOAD(avenrun[2], EXP_15, fp_active_tasks);
+		}
 	}
 }