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Commit ee480683 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Convert se_device statistics to atomic_long_t 



This patch converts the handful of se_device statistics to type
atomic_long_t, instead of using se_device->stats_lock when
incrementing these values.

More importantly, go ahead and drop the spinlock usage within
transport_lookup_cmd_lun() fast-path code.

Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 29f4c090

drivers/target/target_core_device.c

+3 −7
Original line number Diff line number Diff line
@@ -130,15 +130,12 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun) 
	/* Directly associate cmd with se_dev */

	se_cmd->se_dev = se_lun->lun_se_dev;



	/* TODO: get rid of this and use atomics for stats */

	dev = se_lun->lun_se_dev;

	spin_lock_irqsave(&dev->stats_lock, flags);

	dev->num_cmds++;

	atomic_long_inc(&dev->num_cmds);

	if (se_cmd->data_direction == DMA_TO_DEVICE)

		dev->write_bytes += se_cmd->data_length;

		atomic_long_add(se_cmd->data_length, &dev->write_bytes);

	else if (se_cmd->data_direction == DMA_FROM_DEVICE)

		dev->read_bytes += se_cmd->data_length;

	spin_unlock_irqrestore(&dev->stats_lock, flags);

		atomic_long_add(se_cmd->data_length, &dev->read_bytes);



	return 0;

}
@@ -1426,7 +1423,6 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name) 
	INIT_LIST_HEAD(&dev->state_list);

	INIT_LIST_HEAD(&dev->qf_cmd_list);

	INIT_LIST_HEAD(&dev->g_dev_node);

	spin_lock_init(&dev->stats_lock);

	spin_lock_init(&dev->execute_task_lock);

	spin_lock_init(&dev->delayed_cmd_lock);

	spin_lock_init(&dev->dev_reservation_lock);

drivers/target/target_core_stat.c

+9 −6
Original line number Diff line number Diff line
@@ -213,7 +213,8 @@ static ssize_t target_stat_scsi_tgt_dev_show_attr_resets( 
	struct se_device *dev =

		container_of(sgrps, struct se_device, dev_stat_grps);



	return snprintf(page, PAGE_SIZE, "%u\n", dev->num_resets);

	return snprintf(page, PAGE_SIZE, "%lu\n",

			atomic_long_read(&dev->num_resets));

}

DEV_STAT_SCSI_TGT_DEV_ATTR_RO(resets);
@@ -396,8 +397,8 @@ static ssize_t target_stat_scsi_lu_show_attr_num_cmds( 
		container_of(sgrps, struct se_device, dev_stat_grps);



	/* scsiLuNumCommands */

	return snprintf(page, PAGE_SIZE, "%llu\n",

			(unsigned long long)dev->num_cmds);

	return snprintf(page, PAGE_SIZE, "%lu\n",

			atomic_long_read(&dev->num_cmds));

}

DEV_STAT_SCSI_LU_ATTR_RO(num_cmds);
@@ -408,7 +409,8 @@ static ssize_t target_stat_scsi_lu_show_attr_read_mbytes( 
		container_of(sgrps, struct se_device, dev_stat_grps);



	/* scsiLuReadMegaBytes */

	return snprintf(page, PAGE_SIZE, "%u\n", (u32)(dev->read_bytes >> 20));

	return snprintf(page, PAGE_SIZE, "%lu\n",

			atomic_long_read(&dev->read_bytes) >> 20);

}

DEV_STAT_SCSI_LU_ATTR_RO(read_mbytes);
@@ -419,7 +421,8 @@ static ssize_t target_stat_scsi_lu_show_attr_write_mbytes( 
		container_of(sgrps, struct se_device, dev_stat_grps);



	/* scsiLuWrittenMegaBytes */

	return snprintf(page, PAGE_SIZE, "%u\n", (u32)(dev->write_bytes >> 20));

	return snprintf(page, PAGE_SIZE, "%lu\n",

			atomic_long_read(&dev->write_bytes) >> 20);

}

DEV_STAT_SCSI_LU_ATTR_RO(write_mbytes);
@@ -430,7 +433,7 @@ static ssize_t target_stat_scsi_lu_show_attr_resets( 
		container_of(sgrps, struct se_device, dev_stat_grps);



	/* scsiLuInResets */

	return snprintf(page, PAGE_SIZE, "%u\n", dev->num_resets);

	return snprintf(page, PAGE_SIZE, "%lu\n", atomic_long_read(&dev->num_resets));

}

DEV_STAT_SCSI_LU_ATTR_RO(resets);

drivers/target/target_core_tmr.c

+1 −3
Original line number Diff line number Diff line
@@ -386,9 +386,7 @@ int core_tmr_lun_reset( 
		pr_debug("LUN_RESET: SCSI-2 Released reservation\n");

	}



	spin_lock_irq(&dev->stats_lock);

	dev->num_resets++;

	spin_unlock_irq(&dev->stats_lock);

	atomic_long_inc(&dev->num_resets);



	pr_debug("LUN_RESET: %s for [%s] Complete\n",

			(preempt_and_abort_list) ? "Preempt" : "TMR",

include/target/target_core_base.h

+4 −5
Original line number Diff line number Diff line
@@ -683,11 +683,10 @@ struct se_device { 
	/* Pointer to transport specific device structure */

	u32			dev_index;

	u64			creation_time;

	u32			num_resets;

	u64			num_cmds;

	u64			read_bytes;

	u64			write_bytes;

	spinlock_t		stats_lock;

	atomic_long_t		num_resets;

	atomic_long_t		num_cmds;

	atomic_long_t		read_bytes;

	atomic_long_t		write_bytes;

	/* Active commands on this virtual SE device */

	atomic_t		simple_cmds;

	atomic_t		dev_ordered_id;