diff options
| -rw-r--r-- | Documentation/ABI/stable/sysfs-block | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block index aa1e94169666..09a9d4aca0fd 100644 --- a/Documentation/ABI/stable/sysfs-block +++ b/Documentation/ABI/stable/sysfs-block @@ -613,34 +613,45 @@ What: /sys/block/<disk>/queue/async_depth Date: August 2025 Contact: linux-block@vger.kernel.org Description: - [RW] Controls how many asynchronous requests may be allocated in the - block layer. The value is always capped at nr_requests. + [RW] Controls how many asynchronous requests may be allocated + in the block layer. The value is always capped at nr_requests. When no elevator is active (none): + - async_depth is always equal to nr_requests. For bfq scheduler: + - By default, async_depth is set to 75% of nr_requests. Internal limits are then derived from this value: + * Sync writes: limited to async_depth (≈75% of nr_requests). - * Async I/O: limited to ~2/3 of async_depth (≈50% of nr_requests). + * Async I/O: limited to ~2/3 of async_depth (≈50% of + nr_requests). If a bfq_queue is weight-raised: - * Sync writes: limited to ~1/2 of async_depth (≈37% of nr_requests). - * Async I/O: limited to ~1/4 of async_depth (≈18% of nr_requests). - - If the user writes a custom value to async_depth, BFQ will recompute - these limits proportionally based on the new value. + * Sync writes: limited to ~1/2 of async_depth (≈37% of + nr_requests). + * Async I/O: limited to ~1/4 of async_depth (≈18% of + nr_requests). + + - If the user writes a custom value to async_depth, BFQ will + recompute these limits proportionally based on the new value. For Kyber: + - By default async_depth is set to 75% of nr_requests. - - If the user writes a custom value to async_depth, then it override the - default and directly control the limit for writes and async I/O. + - If the user writes a custom value to async_depth, then it + overrides the default and directly controls the limit for + writes and async I/O. For mq-deadline: + - By default async_depth is set to nr_requests. - - If the user writes a custom value to async_depth, then it override the - default and directly control the limit for writes and async I/O. + - If the user writes a custom value to async_depth, then it + overrides the default and directly controls the limit for + writes and async I/O. What: /sys/block/<disk>/queue/nr_zones |