diff options
| author | Ming Lei <ming.lei@redhat.com> | 2025-03-27 17:51:15 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-03-28 16:15:43 -0600 |
| commit | ebf695f129367ed4b26df6baec2ea7fc50c9e6f0 (patch) | |
| tree | d6a1285aef53c81cb8b4f62d3b060ed42983907c /drivers/block | |
| parent | b460f328e257db6af0d127fc8a2437f64ad01d3a (diff) | |
ublk: add segment parameter
IO split is usually bad in io_uring world, since -EAGAIN is caused and
IO handling may have to fallback to io-wq, this way does hurt performance.
ublk starts to support zero copy recently, for avoiding unnecessary IO
split, ublk driver's segment limit should be aligned with backend
device's segment limit.
Another reason is that io_buffer_register_bvec() needs to allocate bvecs,
which number is aligned with ublk request segment number, so that big
memory allocation can be avoided by setting reasonable max_segments limit.
So add segment parameter for providing ublk server chance to align
segment limit with backend, and keep it reasonable from implementation
viewpoint.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250327095123.179113-7-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/ublk_drv.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 1e11816d0b90..a5bcf3aa9d8c 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -74,7 +74,7 @@ #define UBLK_PARAM_TYPE_ALL \ (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \ UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED | \ - UBLK_PARAM_TYPE_DMA_ALIGN) + UBLK_PARAM_TYPE_DMA_ALIGN | UBLK_PARAM_TYPE_SEGMENT) struct ublk_rq_data { struct kref ref; @@ -580,6 +580,18 @@ static int ublk_validate_params(const struct ublk_device *ub) return -EINVAL; } + if (ub->params.types & UBLK_PARAM_TYPE_SEGMENT) { + const struct ublk_param_segment *p = &ub->params.seg; + + if (!is_power_of_2(p->seg_boundary_mask + 1)) + return -EINVAL; + + if (p->seg_boundary_mask + 1 < UBLK_MIN_SEGMENT_SIZE) + return -EINVAL; + if (p->max_segment_size < UBLK_MIN_SEGMENT_SIZE) + return -EINVAL; + } + return 0; } @@ -2370,6 +2382,12 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd) if (ub->params.types & UBLK_PARAM_TYPE_DMA_ALIGN) lim.dma_alignment = ub->params.dma.alignment; + if (ub->params.types & UBLK_PARAM_TYPE_SEGMENT) { + lim.seg_boundary_mask = ub->params.seg.seg_boundary_mask; + lim.max_segment_size = ub->params.seg.max_segment_size; + lim.max_segments = ub->params.seg.max_segments; + } + if (wait_for_completion_interruptible(&ub->completion) != 0) return -EINTR; |