Commit dd9cd435 authored by Seth Howell's avatar Seth Howell Committed by Jim Harris
Browse files

bdev: add tracking for time spent processing I/O. 



Two extra fields are added to the iostat rpc.
1. io_time. The amount of time since queue depth tracking was
enabled that has been spent on I/O processing.
2. weighted_io_time. Incremented each time this bdev's queue depth is
polled by the amount of time spent processing I/O since the last polling
event times the measured queue depth.

Change-Id: Ie70489ec24dee83f3eeac8f4f813ec7074ff458f
Signed-off-by: default avatarSeth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/419031


Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
parent c9f4db30

include/spdk/bdev.h

+34 −0
Original line number Diff line number Diff line
@@ -430,6 +430,40 @@ spdk_bdev_get_qd_sampling_period(const struct spdk_bdev *bdev); 
 */

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



/**

 * Get the time spent processing IO for this device.

 *

 * This value is dependent upon the queue depth sampling period and is

 * incremented at sampling time by the sampling period only if the measured

 * queue depth is greater than 0.

 *

 * The disk utilization can be calculated by the following formula:

 * disk_util = (io_time_2 - io_time_1) / elapsed_time.

 * The user is responsible for tracking the elapsed time between two measurements.

 *

 * \param bdev Block device to query.

 *

 * \return The io time for this device in microseconds.

 */

uint64_t spdk_bdev_get_io_time(const struct spdk_bdev *bdev);



/**

 * Get the weighted IO processing time for this bdev.

 *

 * This value is dependent upon the queue depth sampling period and is

 * equal to the time spent reading from or writing to a device times

 * the measured queue depth during each sampling period.

 *

 * The average queue depth can be calculated by the following formula:

 * queue_depth = (weighted_io_time_2 - weighted_io_time_1) / elapsed_time.

 * The user is responsible for tracking the elapsed time between two measurements.

 *

 * \param bdev Block device to query.

 *

 * \return The weighted io time for this device in microseconds.

 */

uint64_t spdk_bdev_get_weighted_io_time(const struct spdk_bdev *bdev);



/**

 * 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

include/spdk/bdev_module.h

+6 −0
Original line number Diff line number Diff line
@@ -318,6 +318,12 @@ struct spdk_bdev { 
		/** queue depth as calculated the last time the telemetry poller checked. */

		uint64_t measured_queue_depth;



		/** most recent value of ticks spent performing I/O. Used to calculate the weighted time doing I/O */

		uint64_t io_time;



		/** weighted time performing I/O. Equal to measured_queue_depth * period */

		uint64_t weighted_io_time;



	} internal;

};

lib/bdev/bdev.c

+16 −0
Original line number Diff line number Diff line
@@ -1641,12 +1641,28 @@ spdk_bdev_get_qd_sampling_period(const struct spdk_bdev *bdev) 
	return bdev->internal.period;

}



uint64_t

spdk_bdev_get_weighted_io_time(const struct spdk_bdev *bdev)

{

	return bdev->internal.weighted_io_time;

}



uint64_t

spdk_bdev_get_io_time(const struct spdk_bdev *bdev)

{

	return bdev->internal.io_time;

}



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;



	if (bdev->internal.measured_queue_depth) {

		bdev->internal.weighted_io_time += bdev->internal.period * bdev->internal.measured_queue_depth;

	}

}



static void

lib/bdev/rpc/bdev_rpc.c

+6 −0
Original line number Diff line number Diff line
@@ -88,6 +88,12 @@ spdk_rpc_get_bdevs_iostat_cb(struct spdk_bdev *bdev, 


			spdk_json_write_name(w, "queue_depth");

			spdk_json_write_uint64(w, spdk_bdev_get_qd(bdev));



			spdk_json_write_name(w, "io_time");

			spdk_json_write_uint64(w, spdk_bdev_get_io_time(bdev));



			spdk_json_write_name(w, "weighted_io_time");

			spdk_json_write_uint64(w, spdk_bdev_get_weighted_io_time(bdev));

		}



		spdk_json_write_object_end(w);