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Diffstat (limited to 'Documentation/block/bfq-iosched.txt')
| -rw-r--r-- | Documentation/block/bfq-iosched.txt | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt index cbf85f6f1fd87..461b27fce979c 100644 --- a/Documentation/block/bfq-iosched.txt +++ b/Documentation/block/bfq-iosched.txt @@ -253,9 +253,14 @@ of slice_idle are copied from CFQ too. per-process ioprio and weight ----------------------------- -Unless the cgroups interface is used, weights can be assigned to -processes only indirectly, through I/O priorities, and according to -the relation: weight = (IOPRIO_BE_NR - ioprio) * 10. +Unless the cgroups interface is used (see "4. BFQ group scheduling"), +weights can be assigned to processes only indirectly, through I/O +priorities, and according to the relation: +weight = (IOPRIO_BE_NR - ioprio) * 10. + +Beware that, if low-latency is set, then BFQ automatically raises the +weight of the queues associated with interactive and soft real-time +applications. Unset this tunable if you need/want to control weights. slice_idle ---------- @@ -450,9 +455,9 @@ may be reactivated for an already busy async queue (in ms). 4. Group scheduling with BFQ ============================ -BFQ supports both cgroup-v1 and cgroup-v2 io controllers, namely blkio -and io. In particular, BFQ supports weight-based proportional -share. +BFQ supports both cgroups-v1 and cgroups-v2 io controllers, namely +blkio and io. In particular, BFQ supports weight-based proportional +share. To activate cgroups support, set BFQ_GROUP_IOSCHED. 4-1 Service guarantees provided ------------------------------- |