Implement a simple LRU block cache. By default this is initialised to 16k,

and will bypass transfers for more than 8k.  Blocks are invalidated after
2 seconds, so removable media should not confuse the cache.

The 8k threshold is a compromise; all UFS transfers performed by
libstand are 8k or less, so large file reads thrash the cache.
However many filesystem metadata operations are also performed using
8k blocks, so using a lower threshold gives poor performance.

Those of you with an eye for cache algorithms are welcome to tell me
how badly this one sucks; you can start with the 'bcachestats' command
which will print the contents of the cache and access statistics.

2 files changed, 19 insertions, 7 deletions

diff --git a/sys/boot/alpha/common/main.c b/sys/boot/alpha/common/main.c
index 2776b08..4140024 100644
--- a/sys/boot/alpha/common/main.c
+++ b/sys/boot/alpha/common/main.c
@@ -24,7 +24,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: main.c,v 1.7 1998/10/24 00:31:21 msmith Exp $
+ *	$Id: main.c,v 1.8 1998/10/31 17:12:32 dfr Exp $
  */
 
 
@@ -142,6 +142,11 @@ main(void)
     OSFpal();
 
     /*
+     * Initialise the block cache
+     */
+    bcache_init(32, 512);	/* 16k XXX tune this */
+
+    /*
      * March through the device switch probing for things.
      */
     for (i = 0; devsw[i] != NULL; i++)
diff --git a/sys/boot/alpha/libalpha/srmdisk.c b/sys/boot/alpha/libalpha/srmdisk.c
index bd74ba7..f071e15 100644
--- a/sys/boot/alpha/libalpha/srmdisk.c
+++ b/sys/boot/alpha/libalpha/srmdisk.c
@@ -24,7 +24,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: srmdisk.c,v 1.1.1.1 1998/08/21 03:17:42 msmith Exp $
+ *	$Id: srmdisk.c,v 1.2 1998/10/31 17:12:32 dfr Exp $
  */
 
 /*
@@ -61,6 +61,7 @@
 
 static int	bd_init(void);
 static int	bd_strategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize);
+static int	bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize);
 static int	bd_open(struct open_file *f, void *vdev);
 static int	bd_close(struct open_file *f);
 static void	bd_print(int verbose);
@@ -70,10 +71,6 @@ struct open_disk {
     int			od_unit;		/* our unit number */
     int			od_boff;		/* block offset from beginning of SRM disk */
     int			od_flags;
-#define	BD_MODEMASK	0x3
-#define BD_MODEINT13	0x0
-#define BD_MODEEDD1	0x1
-#define BD_MODEEDD3	0x2
 #define BD_FLOPPY	(1<<2)
     u_char		od_buf[BUFSIZE];	/* transfer buffer (do we want/need this?) */
 };
@@ -326,7 +323,17 @@ bd_close(struct open_file *f)
 }
 
 static int 
-bd_strategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize)
+bd_strategy(void *devdata, int rw, daddr_t dblk, size_t size, void *buf, size_t *rsize)
+{
+    struct bcache_devdata	bcd;
+    
+    bcd.dv_strategy = bd_realstrategy;
+    bcd.dv_devdata = devdata;
+    return(bcache_strategy(&bcd, rw, dblk, size, buf, rsize));
+}
+
+static int 
+bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize)
 {
     prom_return_t	ret;
     struct open_disk	*od = (struct open_disk *)devdata;