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Commit f890f579 authored by Mike Christie's avatar Mike Christie Committed by Nicholas Bellinger
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tcmu: simplify dbi thresh handling 



We do not really save a lot by trying to increase thresh
a multiple of the existing value. This just simplifies the
code by increasing it to whatever is needed for the command
being executed.

Signed-off-by: default avatarMike Christie <mchristi@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 6fd0ce79

drivers/target/target_core_user.c

+3 −19
Original line number Diff line number Diff line
@@ -79,7 +79,6 @@ 
#define DATA_BLOCK_SIZE PAGE_SIZE

#define DATA_BLOCK_BITS (256 * 1024)

#define DATA_SIZE (DATA_BLOCK_BITS * DATA_BLOCK_SIZE)

#define DATA_BLOCK_INIT_BITS 128



/* The total size of the ring is 8M + 256K * PAGE_SIZE */

#define TCMU_RING_SIZE (CMDR_SIZE + DATA_SIZE)
@@ -700,7 +699,6 @@ static bool is_ring_space_avail(struct tcmu_dev *udev, struct tcmu_cmd *cmd, 
	if ((space * DATA_BLOCK_SIZE) < data_needed) {

		unsigned long blocks_left = DATA_BLOCK_BITS - udev->dbi_thresh +

						space;

		unsigned long grow;



		if (blocks_left < blocks_needed) {

			pr_debug("no data space: only %lu available, but ask for %zu\n",
@@ -709,24 +707,10 @@ static bool is_ring_space_avail(struct tcmu_dev *udev, struct tcmu_cmd *cmd, 
			return false;

		}



		/* Try to expand the thresh */

		if (!udev->dbi_thresh) {

			/* From idle state */

			uint32_t init_thresh = DATA_BLOCK_INIT_BITS;



			udev->dbi_thresh = max(blocks_needed, init_thresh);

		} else {

			/*

			 * Grow the data area by max(blocks needed,

			 * dbi_thresh / 2), but limited to the max

			 * DATA_BLOCK_BITS size.

			 */

			grow = max(blocks_needed, udev->dbi_thresh / 2);

			udev->dbi_thresh += grow;

		udev->dbi_thresh += blocks_needed;

		if (udev->dbi_thresh > DATA_BLOCK_BITS)

			udev->dbi_thresh = DATA_BLOCK_BITS;

	}

	}



	return tcmu_get_empty_blocks(udev, cmd);

}