Commit 02be32d4 authored by lorneli's avatar lorneli Committed by Darek Stojaczyk
Browse files

bdev: optimize coversion of bytes to blocks 



Since division is more expensive than right shift operator, in
function spdk_bdev_bytes_to_blocks, use right shift instead of
division if the blocklen of bdev is a power of two.

Change-Id: Ib3dbc792e86582bba30b3dc028efbd12c69075ba
Signed-off-by: default avatarlorneli <lorneli@163.com>
Reviewed-on: https://review.gerrithub.io/438318


Reviewed-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: default avatarPawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
Reviewed-by: default avatarDarek Stojaczyk <dariusz.stojaczyk@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
parent eb6bac0a

lib/bdev/bdev.c

+14 −5
Original line number Diff line number Diff line
@@ -2304,12 +2304,21 @@ spdk_bdev_bytes_to_blocks(struct spdk_bdev *bdev, uint64_t offset_bytes, uint64_ 
			  uint64_t num_bytes, uint64_t *num_blocks)

{

	uint32_t block_size = bdev->blocklen;

	uint8_t shift_cnt;



	/* Avoid expensive div operations if possible. These spdk_u32 functions are very cheap. */

	if (spdk_likely(spdk_u32_is_pow2(block_size))) {

		shift_cnt = spdk_u32log2(block_size);

		*offset_blocks = offset_bytes >> shift_cnt;

		*num_blocks = num_bytes >> shift_cnt;

		return (offset_bytes - (*offset_blocks << shift_cnt)) |

		       (num_bytes - (*num_blocks << shift_cnt));

	} else {

		*offset_blocks = offset_bytes / block_size;

		*num_blocks = num_bytes / block_size;



		return (offset_bytes % block_size) | (num_bytes % block_size);

	}

}



static bool

spdk_bdev_io_valid_blocks(struct spdk_bdev *bdev, uint64_t offset_blocks, uint64_t num_blocks)

test/unit/lib/bdev/bdev.c/bdev_ut.c

+12 −0
Original line number Diff line number Diff line
@@ -546,6 +546,18 @@ bytes_to_blocks_test(void) 


	/* Length not a block multiple */

	CU_ASSERT(spdk_bdev_bytes_to_blocks(&bdev, 512, &offset_blocks, 3, &num_blocks) != 0);



	/* In case blocklen not the power of two */

	bdev.blocklen = 100;

	CU_ASSERT(spdk_bdev_bytes_to_blocks(&bdev, 100, &offset_blocks, 200, &num_blocks) == 0);

	CU_ASSERT(offset_blocks == 1);

	CU_ASSERT(num_blocks == 2);



	/* Offset not a block multiple */

	CU_ASSERT(spdk_bdev_bytes_to_blocks(&bdev, 3, &offset_blocks, 100, &num_blocks) != 0);



	/* Length not a block multiple */

	CU_ASSERT(spdk_bdev_bytes_to_blocks(&bdev, 100, &offset_blocks, 3, &num_blocks) != 0);

}



static void