tree 1dd29e4f8ae3122d8cc642523a6f0cd2ca70bfd3
parent fc789a93994858b5e5a46afb96d0dcf6cc1b6f08
author Mark Haverkamp <[EMAIL PROTECTED]> Thu, 04 Aug 2005 05:38:51 -0700
committer James Bottomley <[EMAIL PROTECTED](none)> Sat, 06 Aug 2005 02:49:46 
-0500

[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 <[EMAIL PROTECTED]>
Signed-off-by: James Bottomley <[EMAIL PROTECTED]>

 drivers/scsi/aacraid/comminit.c |    4 +++-
 drivers/scsi/aacraid/commsup.c  |   20 +++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/aacraid/comminit.c b/drivers/scsi/aacraid/comminit.c
--- 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
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -254,6 +254,7 @@ static void fib_dealloc(struct fib * fib
 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
         */
 
        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)
-
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