[PATCH] cciss: direct lookup for command completions

This patch changes the way we complete commands.  In the old method when we
got a completion we searched our command list from the top until we find it.

This method uses a tag associated with each command (not SCSI command tagging)
to index us directly to the completed command.  This helps performance.

Signed-off-by: Don Brace <dab@hp.com>
Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/block/cciss_cmd.h b/drivers/block/cciss_cmd.h
index a88a88817623..53fea549ba8b 100644
--- a/drivers/block/cciss_cmd.h
+++ b/drivers/block/cciss_cmd.h
@@ -226,6 +226,10 @@ typedef struct _ErrorInfo_struct {
 #define CMD_MSG_DONE    0x04
 #define CMD_MSG_TIMEOUT 0x05
 
+/* This structure needs to be divisible by 8 for new
+ * indexing method.
+ */
+#define PADSIZE (sizeof(long) - 4)
 typedef struct _CommandList_struct {
   CommandListHeader_struct Header;
   RequestBlock_struct      Request;
@@ -236,14 +240,14 @@ typedef struct _CommandList_struct {
   ErrorInfo_struct *       err_info; /* pointer to the allocated mem */ 
   int                      ctlr;
   int                      cmd_type; 
+  long                     cmdindex;
   struct _CommandList_struct *prev;
   struct _CommandList_struct *next;
   struct request *         rq;
   struct completion *waiting;
   int    retry_count;
-#ifdef CONFIG_CISS_SCSI_TAPE
   void * scsi_cmd;
-#endif
+  char   pad[PADSIZE];
 } CommandList_struct;
 
 //Configuration Table Structure