[SCSI] lpfc 8.1.1 : Add polled-mode support

- Add functionality to run in polled mode only. Includes run time
  attribute to enable mode.
- Enable runtime writable hba settings for coallescing and delay parameters

Customers have requested a mode in the driver to run strictly polled.
This is generally to support an environment where the server is extremely
loaded and is looking to reclaim some cpu cycles from adapter interrupt
handling.

This patch adds a new "poll" attribute, and the following behavior:

if value is 0 (default):
  The driver uses the normal method for i/o completion. It uses the
  firmware feature of interrupt coalesing. The firmware allows a
  minimum number of i/o completions before an interrupt, or a maximum
  time delay between interrupts.  By default, the driver sets these
  to no delay (disabled) or 1 i/o - meaning coalescing is disabled.

  Attributes were provided to change the coalescing values, but it was
  a module-load time only and global across all adapters.
  This patch allows them to be writable on a per-adapter basis.

if value is 1 :
  Interrupts are left enabled, expecting that the user has tuned the
  interrupt coalescing values. When this setting is enabled, the driver
  will attempt to service completed i/o whenever new i/o is submitted
  to the adapter. If the coalescing values are large, and the i/o
  generation rate steady, an interrupt will be avoided by servicing
  completed i/o prior to the coalescing thresholds kicking in. However,
  if the i/o completion load is high enough or i/o generation slow, the
  coalescion values will ensure that completed i/o is serviced in a timely
  fashion.

if value is 3 :
  Turns off FCP i/o interrupts altogether. The coalescing values now have
  no effect. A new attribute "poll_tmo" (default 10ms) exists to set
  the polling interval for i/o completion. When this setting is enabled,
  the driver will attempt to service completed i/o and restart the
  interval timer whenever new i/o is submitted. This behavior allows for
  servicing of completed i/o sooner than the interval timer, but ensures
  that if no i/o is being issued, then the interval timer will kick in
  to service the outstanding i/o.

Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 62 insertions, 10 deletions

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 7dc7810b7482..c422220db0ae 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -151,18 +151,22 @@ lpfc_new_scsi_buf(struct lpfc_hba * phba)
 }
 
 struct  lpfc_scsi_buf*
-lpfc_sli_get_scsi_buf(struct lpfc_hba * phba)
+lpfc_get_scsi_buf(struct lpfc_hba * phba)
 {
         struct  lpfc_scsi_buf * lpfc_cmd = NULL;
         struct list_head *scsi_buf_list = &phba->lpfc_scsi_buf_list;
+        unsigned long iflag = 0;
 
+        spin_lock_irqsave(&phba->scsi_buf_list_lock, iflag);
         list_remove_head(scsi_buf_list, lpfc_cmd, struct lpfc_scsi_buf, list);
+        spin_unlock_irqrestore(&phba->scsi_buf_list_lock, iflag);
         return  lpfc_cmd;
 }
 
 static void
 lpfc_release_scsi_buf(struct lpfc_hba * phba, struct lpfc_scsi_buf * psb)
 {
+        unsigned long iflag = 0;
         /*
          * There are only two special cases to consider.  (1) the scsi command
          * requested scatter-gather usage or (2) the scsi command allocated
@@ -180,8 +184,10 @@ lpfc_release_scsi_buf(struct lpfc_hba * phba, struct lpfc_scsi_buf * psb)
                  }
         }
 
+        spin_lock_irqsave(&phba->scsi_buf_list_lock, iflag);
         psb->pCmd = NULL;
         list_add_tail(&psb->list, &phba->lpfc_scsi_buf_list);
+        spin_unlock_irqrestore(&phba->scsi_buf_list_lock, iflag);
 }
 
 static int
@@ -403,7 +409,6 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
         struct lpfc_rport_data *rdata = lpfc_cmd->rdata;
         struct lpfc_nodelist *pnode = rdata->pnode;
         struct scsi_cmnd *cmd = lpfc_cmd->pCmd;
-        unsigned long iflag;
 
         lpfc_cmd->result = pIocbOut->iocb.un.ulpWord[4];
         lpfc_cmd->status = pIocbOut->iocb.ulpStatus;
@@ -457,9 +462,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 
         cmd->scsi_done(cmd);
 
-        spin_lock_irqsave(phba->host->host_lock, iflag);
         lpfc_release_scsi_buf(phba, lpfc_cmd);
-        spin_unlock_irqrestore(phba->host->host_lock, iflag);
 }
 
 static void
@@ -707,6 +710,37 @@ lpfc_info(struct Scsi_Host *host)
         return lpfcinfobuf;
 }
 
+static __inline__ void lpfc_poll_rearm_timer(struct lpfc_hba * phba)
+{
+        unsigned long  poll_tmo_expires =
+                (jiffies + msecs_to_jiffies(phba->cfg_poll_tmo));
+
+        if (phba->sli.ring[LPFC_FCP_RING].txcmplq_cnt)
+                mod_timer(&phba->fcp_poll_timer,
+                          poll_tmo_expires);
+}
+
+void lpfc_poll_start_timer(struct lpfc_hba * phba)
+{
+        lpfc_poll_rearm_timer(phba);
+}
+
+void lpfc_poll_timeout(unsigned long ptr)
+{
+        struct lpfc_hba *phba = (struct lpfc_hba *)ptr;
+        unsigned long iflag;
+
+        spin_lock_irqsave(phba->host->host_lock, iflag);
+
+        if (phba->cfg_poll & ENABLE_FCP_RING_POLLING) {
+                lpfc_sli_poll_fcp_ring (phba);
+                if (phba->cfg_poll & DISABLE_FCP_RING_INT)
+                        lpfc_poll_rearm_timer(phba);
+        }
+
+        spin_unlock_irqrestore(phba->host->host_lock, iflag);
+}
+
 static int
 lpfc_queuecommand(struct scsi_cmnd *cmnd, void (*done) (struct scsi_cmnd *))
 {
@@ -733,7 +767,7 @@ lpfc_queuecommand(struct scsi_cmnd *cmnd, void (*done) (struct scsi_cmnd *))
                 cmnd->result = ScsiResult(DID_BUS_BUSY, 0);
                 goto out_fail_command;
         }
-        lpfc_cmd = lpfc_sli_get_scsi_buf (phba);
+        lpfc_cmd = lpfc_get_scsi_buf (phba);
         if (lpfc_cmd == NULL) {
                 lpfc_printf_log(phba, KERN_INFO, LOG_FCP,
                                 "%d:0707 driver's buffer pool is empty, "
@@ -761,11 +795,17 @@ lpfc_queuecommand(struct scsi_cmnd *cmnd, void (*done) (struct scsi_cmnd *))
                                 &lpfc_cmd->cur_iocbq, SLI_IOCB_RET_IOCB);
         if (err)
                 goto out_host_busy_free_buf;
+
+        if (phba->cfg_poll & ENABLE_FCP_RING_POLLING) {
+                lpfc_sli_poll_fcp_ring(phba);
+                if (phba->cfg_poll & DISABLE_FCP_RING_INT)
+                        lpfc_poll_rearm_timer(phba);
+        }
+
         return 0;
 
  out_host_busy_free_buf:
         lpfc_release_scsi_buf(phba, lpfc_cmd);
-        cmnd->host_scribble = NULL;
  out_host_busy:
         return SCSI_MLQUEUE_HOST_BUSY;
 
@@ -839,9 +879,15 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
                 goto out;
         }
 
+        if (phba->cfg_poll & DISABLE_FCP_RING_INT)
+                lpfc_sli_poll_fcp_ring (phba);
+
         /* Wait for abort to complete */
         while (lpfc_cmd->pCmd == cmnd)
         {
+                if (phba->cfg_poll & DISABLE_FCP_RING_INT)
+                        lpfc_sli_poll_fcp_ring (phba);
+
                 spin_unlock_irq(phba->host->host_lock);
                         schedule_timeout_uninterruptible(LPFC_ABORT_WAIT*HZ);
                 spin_lock_irq(phba->host->host_lock);
@@ -905,7 +951,7 @@ lpfc_reset_lun_handler(struct scsi_cmnd *cmnd)
                         break;
         }
 
-        lpfc_cmd = lpfc_sli_get_scsi_buf (phba);
+        lpfc_cmd = lpfc_get_scsi_buf (phba);
         if (lpfc_cmd == NULL)
                 goto out;
 
@@ -1001,7 +1047,7 @@ lpfc_reset_bus_handler(struct scsi_cmnd *cmnd)
         lpfc_block_requests(phba);
         spin_lock_irq(shost->host_lock);
 
-        lpfc_cmd = lpfc_sli_get_scsi_buf (phba);
+        lpfc_cmd = lpfc_get_scsi_buf(phba);
         if (lpfc_cmd == NULL)
                 goto out;
 
@@ -1136,10 +1182,10 @@ lpfc_slave_alloc(struct scsi_device *sdev)
                         break;
                 }
 
-                spin_lock_irqsave(phba->host->host_lock, flags);
+                spin_lock_irqsave(&phba->scsi_buf_list_lock, flags);
                 phba->total_scsi_bufs++;
                 list_add_tail(&scsi_buf->list, &phba->lpfc_scsi_buf_list);
-                spin_unlock_irqrestore(phba->host->host_lock, flags);
+                spin_unlock_irqrestore(&phba->scsi_buf_list_lock, flags);
         }
         return 0;
 }
@@ -1163,6 +1209,12 @@ lpfc_slave_configure(struct scsi_device *sdev)
          */
         rport->dev_loss_tmo = phba->cfg_nodev_tmo + 5;
 
+        if (phba->cfg_poll & ENABLE_FCP_RING_POLLING) {
+                lpfc_sli_poll_fcp_ring(phba);
+                if (phba->cfg_poll & DISABLE_FCP_RING_INT)
+                        lpfc_poll_rearm_timer(phba);
+        }
+
         return 0;
 }