From: Alan Cox <alan@etchedpixels.co.uk>
Date: Tue, 25 Nov 2014 11:00:42 +0000 (+0000)
Subject: process: Add loadav calculator.
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=4cc69c5c002acbc972e6b766cb5060791ab545db;p=FUZIX.git

process: Add loadav calculator.

Needs to be exposed nicely to userspace yet.

Also remove a dead FIXME in the process code
---

diff --git a/Kernel/include/kdata.h b/Kernel/include/kdata.h
index 7524c085..e12fe7c0 100644
--- a/Kernel/include/kdata.h
+++ b/Kernel/include/kdata.h
@@ -60,6 +60,15 @@ typedef struct devsw {
 
 extern struct devsw dev_tab[];
 
+// Load management
+struct runload {
+	/* exponent is 8.8 fixed point */
+	uint8_t exponent;
+	uint16_t average;
+};
+
+extern struct runload loadavg[];
+
 // the system call dispatch table
 #define UZI_SYSCALL_COUNT 61
 typedef int16_t (*syscall_t)(void);
diff --git a/Kernel/kdata.c b/Kernel/kdata.c
index 98494fef..39d92dac 100644
--- a/Kernel/kdata.c
+++ b/Kernel/kdata.c
@@ -18,6 +18,12 @@ clock_t ticks;			// system tick counter
 
 int16_t acct_fh = -1;		/* Accounting file handle */
 
+struct runload loadavg[3] = {
+	{ 235, 0 },	/* 12 sets of 5 seconds per minute */
+	{ 251, 0 },	/* 60 sets of 5 seconds per 5 minutes */
+	{ 254, 0 }	/* 180 sets of 5 seconds per 15 minutes */
+};
+
 /* We keep the boot up strings in the buffer pool then toss them! 8) */
 
 struct blkbuf bufpool[NBUFS] = {
diff --git a/Kernel/process.c b/Kernel/process.c
index 6d599019..647a28b4 100644
--- a/Kernel/process.c
+++ b/Kernel/process.c
@@ -1,6 +1,6 @@
 #undef DEBUG			/* turn this on to enable syscall tracing */
 #undef DEBUGHARDER		/* report calls to wakeup() that lead nowhere */
-#undef	DEBUGREALLYHARD		/* turn on getproc dumping */
+#undef DEBUGREALLYHARD		/* turn on getproc dumping */
 
 #include <kernel.h>
 #include <timer.h>
@@ -278,6 +278,34 @@ ptptr ptab_alloc(void)
 	return newp;
 }
 
+/* Follow Unix tradition with load reporting (or more accurately it
+   is pre-Unix from Tenex) */
+
+void load_average(void)
+{
+	struct runload *r;
+	static uint8_t utick;
+	uint8_t i;
+	uint8_t nr;
+
+	utick++;
+	if (utick < 50)
+		return;
+
+	utick = 0;
+
+	/* Every 5 seconds */
+	i = 0;
+	r = &loadavg[0];
+	nr = nready;
+
+	while (i++ < 3) {
+		r->average = ((((r->average - (nr << 8)) * r->exponent) +
+				((unsigned long)nr) << 16)) >> 8;
+		r++;
+	}
+}
+
 /* This is the clock interrupt routine.   Its job is to increment the clock
  * counters, increment the tick count of the running process, and either
  * switch it out if it has been in long enough and is in user space or mark
@@ -290,11 +318,12 @@ ptptr ptab_alloc(void)
 void timer_interrupt(void)
 {
 	/* Increment processes and global tick counters */
-	if (udata.u_ptab->p_status == P_RUNNING)
+	if (udata.u_ptab->p_status == P_RUNNING) {
 		if (udata.u_insys)
 			udata.u_stime++;
 		else
 			udata.u_utime++;
+	}
 	ticks++;
 
 	/* Do once-per-decisecond things */
@@ -432,8 +461,6 @@ void chksigs(void)
 			kprintf("about to process signal %d\n", j);
 #endif
 			udata.u_cursig = j;
-			/* FIXME: multiple signal processing here and in
-			   lowlevel-$cpu.s */
 			break;
 		}
 	}