Commit 84c3e1ad authored by Vasu Dev's avatar Vasu Dev Committed by James Bottomley
Browse files

[SCSI] libfc: adds can_queue ramp up 



Adds last_can_queue_ramp_down_time and updates this on every
ramp down. If last_can_queue_ramp_down_time is not zero then
do ramp up on any IO completion in added fc_fcp_can_queue_ramp_up.

Reset last_can_queue_ramp_down_time to zero once can_queue
is ramped up to added max_can_queue limit, this is to avoid any
more ramp up attempts on subsequent IO completion.

The ramp down and up are skipped for FC_CAN_QUEUE_PERIOD
to avoid infrequent changes to can_queue, this required
keeping track of ramp up time also in last_can_queue_ramp_up_time.

Adds code to ramp down can_queue if lp->qfull is set, with added
new ramp up code the can_queue will be increased after
FC_CAN_QUEUE_PERIOD, therefore it is safe to do ramp down
without fsp in this case and will avoid thrash. This required
fc_fcp_can_queue_ramp_down locking change so that it can be
called with Scsi_Host lock held.

Removes si->throttled and fsp state FC_SRB_NOMEM, not needed with
added ramp up code.

Signed-off-by: default avatarVasu Dev <vasu.dev@intel.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
parent c46be11a

drivers/scsi/libfc/fc_fcp.c

+59 −19
Original line number Diff line number Diff line
@@ -52,7 +52,6 @@ struct kmem_cache *scsi_pkt_cachep; 
#define FC_SRB_DISCONTIG	(1 << 4)	/* non-sequential data recvd */

#define FC_SRB_COMPL		(1 << 5)	/* fc_io_compl has been run */

#define FC_SRB_FCP_PROCESSING_TMO (1 << 6)	/* timer function processing */

#define FC_SRB_NOMEM		(1 << 7)	/* dropped to out of mem */



#define FC_SRB_READ		(1 << 1)

#define FC_SRB_WRITE		(1 << 0)
@@ -71,12 +70,16 @@ struct kmem_cache *scsi_pkt_cachep; 
 * struct fc_fcp_internal - FCP layer internal data

 * @scsi_pkt_pool:  Memory pool to draw FCP packets from

 * @scsi_pkt_queue: Current FCP packets

 * @throttled:	    The FCP packet queue is throttled

 * @last_can_queue_ramp_down_time: ramp down time

 * @last_can_queue_ramp_up_time: ramp up time

 * @max_can_queue: max can_queue size

 */

struct fc_fcp_internal {

	mempool_t	 *scsi_pkt_pool;

	struct list_head scsi_pkt_queue;

	u8		 throttled;

	unsigned long last_can_queue_ramp_down_time;

	unsigned long last_can_queue_ramp_up_time;

	int max_can_queue;

};



#define fc_get_scsi_internal(x)	((struct fc_fcp_internal *)(x)->scsi_priv)
@@ -124,6 +127,7 @@ static void fc_fcp_srr_error(struct fc_fcp_pkt *, struct fc_frame *); 
#define FC_SCSI_TM_TOV		(10 * HZ)

#define FC_SCSI_REC_TOV		(2 * HZ)

#define FC_HOST_RESET_TIMEOUT	(30 * HZ)

#define FC_CAN_QUEUE_PERIOD	(60 * HZ)



#define FC_MAX_ERROR_CNT	5

#define FC_MAX_RECOV_RETRY	3
@@ -326,6 +330,38 @@ static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp) 
	}

}



/**

 * fc_fcp_can_queue_ramp_up() - increases can_queue

 * @lport: lport to ramp up can_queue

 *

 * Locking notes: Called with Scsi_Host lock held

 */

static void fc_fcp_can_queue_ramp_up(struct fc_lport *lport)

{

	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);

	int can_queue;



	if (si->last_can_queue_ramp_up_time &&

	    (time_before(jiffies, si->last_can_queue_ramp_up_time +

			 FC_CAN_QUEUE_PERIOD)))

		return;



	if (time_before(jiffies, si->last_can_queue_ramp_down_time +

			FC_CAN_QUEUE_PERIOD))

		return;



	si->last_can_queue_ramp_up_time = jiffies;



	can_queue = lport->host->can_queue << 1;

	if (can_queue >= si->max_can_queue) {

		can_queue = si->max_can_queue;

		si->last_can_queue_ramp_down_time = 0;

	}

	lport->host->can_queue = can_queue;

	shost_printk(KERN_ERR, lport->host, "libfc: increased "

		     "can_queue to %d.\n", can_queue);

}



/**

 * fc_fcp_can_queue_ramp_down() - reduces can_queue

 * @lport: lport to reduce can_queue
@@ -335,17 +371,20 @@ static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp) 
 * commands complete or timeout, then try again with a reduced

 * can_queue. Eventually we will hit the point where we run

 * on all reserved structs.

 *

 * Locking notes: Called with Scsi_Host lock held

 */

static void fc_fcp_can_queue_ramp_down(struct fc_lport *lport)

{

	struct fc_fcp_internal *si = fc_get_scsi_internal(lport);

	unsigned long flags;

	int can_queue;



	spin_lock_irqsave(lport->host->host_lock, flags);

	if (si->throttled)

		goto done;

	si->throttled = 1;

	if (si->last_can_queue_ramp_down_time &&

	    (time_before(jiffies, si->last_can_queue_ramp_down_time +

			 FC_CAN_QUEUE_PERIOD)))

		return;



	si->last_can_queue_ramp_down_time = jiffies;



	can_queue = lport->host->can_queue;

	can_queue >>= 1;
@@ -354,8 +393,6 @@ static void fc_fcp_can_queue_ramp_down(struct fc_lport *lport) 
	lport->host->can_queue = can_queue;

	shost_printk(KERN_ERR, lport->host, "libfc: Could not allocate frame.\n"

		     "Reducing can_queue to %d.\n", can_queue);

done:

	spin_unlock_irqrestore(lport->host->host_lock, flags);

}



/*
@@ -370,10 +407,14 @@ static inline struct fc_frame *fc_fcp_frame_alloc(struct fc_lport *lport, 
						  size_t len)

{

	struct fc_frame *fp;

	unsigned long flags;



	fp = fc_frame_alloc(lport, len);

	if (!fp)

	if (!fp) {

		spin_lock_irqsave(lport->host->host_lock, flags);

		fc_fcp_can_queue_ramp_down(lport);

		spin_unlock_irqrestore(lport->host->host_lock, flags);

	}

	return fp;

}
@@ -720,8 +761,6 @@ static void fc_fcp_recv(struct fc_seq *seq, struct fc_frame *fp, void *arg) 
				      (size_t) ntohl(dd->ft_burst_len));

		if (!rc)

			seq->rec_data = fsp->xfer_len;

		else if (rc == -ENOMEM)

			fsp->state |= FC_SRB_NOMEM;

	} else if (r_ctl == FC_RCTL_DD_SOL_DATA) {

		/*

		 * received a DATA frame
@@ -1734,6 +1773,8 @@ int fc_queuecommand(struct scsi_cmnd *sc_cmd, void (*done)(struct scsi_cmnd *)) 
	rpriv = rport->dd_data;



	if (!fc_fcp_lport_queue_ready(lport)) {

		if (lport->qfull)

			fc_fcp_can_queue_ramp_down(lport);

		rc = SCSI_MLQUEUE_HOST_BUSY;

		goto out;

	}
@@ -1830,13 +1871,11 @@ static void fc_io_compl(struct fc_fcp_pkt *fsp) 
	}



	/*

	 * if a command timed out while we had to try and throttle IO

	 * and it is now getting cleaned up, then we are about to

	 * try again so clear the throttled flag incase we get more

	 * time outs.

	 * if can_queue ramp down is done then try can_queue ramp up

	 * since commands are completing now.

	 */

	if (si->throttled && fsp->state & FC_SRB_NOMEM)

		si->throttled = 0;

	if (si->last_can_queue_ramp_down_time)

		fc_fcp_can_queue_ramp_up(lport);



	sc_cmd = fsp->cmd;

	fsp->cmd = NULL;
@@ -2176,6 +2215,7 @@ int fc_fcp_init(struct fc_lport *lport) 
	if (!si)

		return -ENOMEM;

	lport->scsi_priv = si;

	si->max_can_queue = lport->host->can_queue;

	INIT_LIST_HEAD(&si->scsi_pkt_queue);



	si->scsi_pkt_pool = mempool_create_slab_pool(2, scsi_pkt_cachep);

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