[SCSI] aacraid: interupt mitigation

Received from Mark Salyzyn from Adaptec:

If more than two commands are outstanding to the controller, there is no
need to notify the adapter via a PCI bus transaction of additional
commands added into the queue; it will get to them when it works through
the produce/consumer indexes.

This reduced the PCI traffic in the driver to submit a command to the
queue to near zero allowing a significant number of commands to be
turned around with no need to block for the PCI bridge to flush the
notify request to the adapter.

Interrupt mitigation has always been present in the driver; it was
turned off because of a bug that prevented one from realizing the
usefulness of the feature. This bug is fixed in this patch.

Signed-off-by: Mark Haverkamp <markh@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

diff --git a/drivers/scsi/aacraid/comminit.c b/drivers/scsi/aacraid/comminit.c
index 43557bf661f63098a2754c3fa255b693d02979c2..75abd04532890de2c7855e39bb1551c7886a0468 100644 (file)
--- a/drivers/scsi/aacraid/comminit.c
+++ b/drivers/scsi/aacraid/comminit.c
@@ -44,7 +44,9 @@
 
 #include "aacraid.h"
 
-struct aac_common aac_config;
+struct aac_common aac_config = {
+       .irq_mod = 1
+};
 
 static int aac_alloc_comm(struct aac_dev *dev, void **commaddr, unsigned long commsize, unsigned long commalign)
 {

diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c
index 5322865942e28b1a3911d83a8d2d6104263dd869..a1d303f034808f3e31a2f44860355f1e240d7ee4 100644 (file)
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -254,6 +254,7 @@ static void fib_dealloc(struct fib * fibptr)
 static int aac_get_entry (struct aac_dev * dev, u32 qid, struct aac_entry **entry, u32 * index, unsigned long *nonotify)
 {
        struct aac_queue * q;
+       unsigned long idx;
 
        /*
         *      All of the queues wrap when they reach the end, so we check
@@ -263,10 +264,23 @@ static int aac_get_entry (struct aac_dev * dev, u32 qid, struct aac_entry **entr
         */
 
        q = &dev->queues->queue[qid];
-       
-       *index = le32_to_cpu(*(q->headers.producer));
-       if ((*index - 2) == le32_to_cpu(*(q->headers.consumer)))
+
+       idx = *index = le32_to_cpu(*(q->headers.producer));
+       /* Interrupt Moderation, only interrupt for first two entries */
+       if (idx != le32_to_cpu(*(q->headers.consumer))) {
+               if (--idx == 0) {
+                       if (qid == AdapHighCmdQueue)
+                               idx = ADAP_HIGH_CMD_ENTRIES;
+                       else if (qid == AdapNormCmdQueue)
+                               idx = ADAP_NORM_CMD_ENTRIES;
+                       else if (qid == AdapHighRespQueue) 
+                               idx = ADAP_HIGH_RESP_ENTRIES;
+                       else if (qid == AdapNormRespQueue) 
+                               idx = ADAP_NORM_RESP_ENTRIES;
+               }
+               if (idx != le32_to_cpu(*(q->headers.consumer)))
                        *nonotify = 1; 
+       }
 
        if (qid == AdapHighCmdQueue) {
                if (*index >= ADAP_HIGH_CMD_ENTRIES)