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bdev: optimize coversion of bytes to blocks

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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: lorneli <lorneli@163.com>
Reviewed-on: https://review.gerrithub.io/438318
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
This commit is contained in:
lorneli 2018-12-27 21:12:55 -06:00 committed by Darek Stojaczyk
parent eb6bac0aa9
commit 02be32d482
2 changed files with 25 additions and 4 deletions
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11
lib/bdev/bdev.c
View File

@ -2304,11 +2304,20 @@ 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

12
test/unit/lib/bdev/bdev.c/bdev_ut.c
View File

@ -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