1 files changed, 88 insertions, 0 deletions
diff --git a/src/cmd/venti/srv/disksched.c b/src/cmd/venti/srv/disksched.c
new file mode 100644
index 00000000..687616e1
--- /dev/null
+++ b/src/cmd/venti/srv/disksched.c
@@ -0,0 +1,88 @@
+#include "stdinc.h"
+#include "dat.h"
+#include "fns.h"
+
+ulong lasttime[2];
+int manualscheduling;
+int l0quantum = 120;
+int l1quantum = 120;
+ulong lasticachechange;
+
+void
+disksched(void)
+{
+	int p, nwrite, nflush, ndirty, tdirty, toflush;
+	ulong t;
+	vlong cflush;
+	Stats *prev;
+	
+	/*
+	 * no locks because all the data accesses are atomic.
+	 */
+	t = time(0);
+	if(manualscheduling){
+		lasticachechange = t;
+		return;
+	}
+
+	if(t-lasttime[0] < l0quantum){
+		/* level-0 disk access going on */
+		p = icachedirtyfrac();
+		if(p < IcacheFrac*5/10){	/* can wait */
+			icachesleeptime = SleepForever;
+			lasticachechange = t;
+		}else if(p > IcacheFrac*9/10){	/* can't wait */
+			icachesleeptime = 0;
+			lasticachechange = t;
+		}else if(t-lasticachechange > 60){
+			/* have minute worth of data for current rate */
+			prev = &stathist[(stattime-60+nstathist)%nstathist];
+
+			/* # entries written to index cache */
+			nwrite = stats.n[StatIcacheWrite] - prev->n[StatIcacheWrite];
+			
+			/* # dirty entries in index cache */
+			ndirty = stats.n[StatIcacheDirty] - prev->n[StatIcacheDirty];
+			
+			/* # entries flushed to disk */
+			nflush = nwrite - ndirty;
+			
+			/* want to stay around 70% dirty */
+			tdirty = (vlong)stats.n[StatIcacheSize]*700/1000;
+			
+			/* assume nflush*icachesleeptime is a constant */
+			cflush = (vlong)nflush*(icachesleeptime+1);
+			
+			/* computer number entries to write in next minute */
+			toflush = nwrite + (stats.n[StatIcacheDirty] - tdirty);
+			
+			/* schedule for  that many */
+			if(toflush <= 0 || cflush/toflush > 100000)
+				icachesleeptime = SleepForever;
+			else
+				icachesleeptime = cflush/toflush;
+		}
+		arenasumsleeptime = SleepForever;
+		return;
+	}
+	if(t-lasttime[1] < l1quantum){
+		/* level-1 disk access (icache flush) going on */
+		icachesleeptime = 0;
+		arenasumsleeptime = SleepForever;
+		return;
+	}
+	/* no disk access going on - no holds barred*/
+	icachesleeptime = 0;
+	arenasumsleeptime = 0;
+}
+
+void
+diskaccess(int level)
+{
+	if(level < 0 || level >= nelem(lasttime)){
+		fprint(2, "bad level in diskaccess; caller=%lux\n", getcallerpc(&level));
+		return;
+	}
+	lasttime[level] = time(0);
+}
+