Commit 760b868a authored by Seth Howell's avatar Seth Howell Committed by Jim Harris
Browse files

bdev: add ability to track bdev queue depth. 



This change includes a function to enable this feature on a per-bdev
basis. The new information stored in the bdev includes the following:

measured_queue_depth: The aggregate of the outstanding oparations from
each channel associated with this bdev.
period: The period at which this bdev's measured_queue_depth is being
updated.

With this information, one could calculate the average queue depth and
the disk utilization of the device

Change-Id: Ie0623ee4796e33b125504fb0965d5ef348cbff7d
Signed-off-by: default avatarSeth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/418102


Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
parent 459e8990

include/spdk/bdev.h

+43 −0
Original line number Diff line number Diff line
@@ -389,6 +389,48 @@ bool spdk_bdev_has_write_cache(const struct spdk_bdev *bdev); 
 */

const struct spdk_uuid *spdk_bdev_get_uuid(const struct spdk_bdev *bdev);



/**

 * Get the most recently measured queue depth from a bdev.

 *

 * The reported queue depth is the aggregate of outstanding I/O

 * across all open channels associated with this bdev.

 *

 * \param bdev Block device to query.

 *

 * \return The most recent queue depth measurement for the bdev.

 * If tracking is not enabled, the function will return UINT64_MAX

 * It is also possible to receive UINT64_MAX after enabling tracking

 * but before the first period has expired.

 */

uint64_t

spdk_bdev_get_qd(const struct spdk_bdev *bdev);



/**

 * Get the queue depth polling period.

 *

 * The return value of this function is only valid if the bdev's

 * queue depth tracking status is set to true.

 *

 * \param bdev Block device to query.

 *

 * \return The period at which this bdev's gueue depth is being refreshed.

 */

uint64_t

spdk_bdev_get_qd_sampling_period(const struct spdk_bdev *bdev);



/**

 * Enable or disable queue depth sampling for this bdev.

 *

 * Enables queue depth sampling when period is greater than 0. Disables it when the period

 * is equal to zero. The resulting queue depth is stored in the spdk_bdev object as

 * measured_queue_depth.

 *

 * \param bdev Block device on which to enable queue depth tracking.

 * \param period The period at which to poll this bdev's queue depth. If this is set

 * to zero, polling will be disabled.

 */

void spdk_bdev_set_qd_sampling_period(struct spdk_bdev *bdev, uint64_t period);



/**

 * Obtain an I/O channel for the block device opened by the specified

 * descriptor. I/O channels are bound to threads, so the resulting I/O
@@ -948,6 +990,7 @@ int spdk_bdev_queue_io_wait(struct spdk_bdev *bdev, struct spdk_io_channel *ch, 
void spdk_bdev_get_io_stat(struct spdk_bdev *bdev, struct spdk_io_channel *ch,

			   struct spdk_bdev_io_stat *stat);





/**

 * Return I/O statistics for this bdev. All the required information will be passed

 * via the callback function.

include/spdk/bdev_module.h

+13 −0
Original line number Diff line number Diff line
@@ -306,6 +306,19 @@ struct spdk_bdev { 


		/** points to a reset bdev_io if one is in progress. */

		struct spdk_bdev_io *reset_in_progress;



		/** poller for tracking the queue_depth of a device, NULL if not tracking */

		struct spdk_poller *qd_poller;



		/** period at which we poll for queue depth information */

		uint64_t period;



		/** used to aggregate queue depth while iterating across the bdev's open channels */

		uint64_t temporary_queue_depth;



		/** queue depth as calculated the last time the telemetry poller checked. */

		uint64_t measured_queue_depth;



	} internal;

};

lib/bdev/bdev.c

+60 −0
Original line number Diff line number Diff line
@@ -1642,6 +1642,63 @@ spdk_bdev_get_uuid(const struct spdk_bdev *bdev) 
	return &bdev->uuid;

}



uint64_t

spdk_bdev_get_qd(const struct spdk_bdev *bdev)

{

	return bdev->internal.measured_queue_depth;

}



uint64_t

spdk_bdev_get_qd_sampling_period(const struct spdk_bdev *bdev)

{

	return bdev->internal.period;

}



static void

_calculate_measured_qd_cpl(struct spdk_io_channel_iter *i, int status)

{

	struct spdk_bdev *bdev = spdk_io_channel_iter_get_ctx(i);



	bdev->internal.measured_queue_depth = bdev->internal.temporary_queue_depth;

}



static void

_calculate_measured_qd(struct spdk_io_channel_iter *i)

{

	struct spdk_bdev *bdev = spdk_io_channel_iter_get_ctx(i);

	struct spdk_io_channel *io_ch = spdk_io_channel_iter_get_channel(i);

	struct spdk_bdev_channel *ch = spdk_io_channel_get_ctx(io_ch);



	bdev->internal.temporary_queue_depth += ch->io_outstanding;

	spdk_for_each_channel_continue(i, 0);

}



static int

spdk_bdev_calculate_measured_queue_depth(void *ctx)

{

	struct spdk_bdev *bdev = ctx;

	bdev->internal.temporary_queue_depth = 0;

	spdk_for_each_channel(__bdev_to_io_dev(bdev), _calculate_measured_qd, bdev,

			      _calculate_measured_qd_cpl);

	return 0;

}



void

spdk_bdev_set_qd_sampling_period(struct spdk_bdev *bdev, uint64_t period)

{

	bdev->internal.period = period;



	if (bdev->internal.qd_poller != NULL) {

		spdk_poller_unregister(&bdev->internal.qd_poller);

		bdev->internal.measured_queue_depth = UINT64_MAX;

	}



	if (period != 0) {

		bdev->internal.qd_poller = spdk_poller_register(spdk_bdev_calculate_measured_queue_depth, bdev,

					   period);

	}

}



int

spdk_bdev_notify_blockcnt_change(struct spdk_bdev *bdev, uint64_t size)

{
@@ -2748,6 +2805,7 @@ spdk_bdev_init(struct spdk_bdev *bdev) 
	}



	bdev->internal.status = SPDK_BDEV_STATUS_READY;

	bdev->internal.measured_queue_depth = UINT64_MAX;



	TAILQ_INIT(&bdev->internal.open_descs);
@@ -3091,6 +3149,8 @@ spdk_bdev_close(struct spdk_bdev_desc *desc) 
		}

	}



	spdk_bdev_set_qd_sampling_period(bdev, 0);



	if (bdev->internal.status == SPDK_BDEV_STATUS_REMOVING && TAILQ_EMPTY(&bdev->internal.open_descs)) {

		do_unregister = true;

	}