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Diffstat (limited to 'Documentation/ABI/stable/sysfs-block')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-block | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block index 0ed10aeff86b..09a9d4aca0fd 100644 --- a/Documentation/ABI/stable/sysfs-block +++ b/Documentation/ABI/stable/sysfs-block @@ -609,6 +609,51 @@ Description: enabled, and whether tags are shared. +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. + + 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). + + 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. + + 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 + 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 + overrides the default and directly controls the limit for + writes and async I/O. + + What: /sys/block/<disk>/queue/nr_zones Date: November 2018 Contact: Damien Le Moal <damien.lemoal@wdc.com> |