diff options
Diffstat (limited to 'Documentation/block')
| -rw-r--r-- | Documentation/block/data-integrity.txt | 4 | ||||
| -rw-r--r-- | Documentation/block/deadline-iosched.txt | 14 |
2 files changed, 12 insertions, 6 deletions
diff --git a/Documentation/block/data-integrity.txt b/Documentation/block/data-integrity.txt index e9dc8d86adc..e8ca040ba2c 100644 --- a/Documentation/block/data-integrity.txt +++ b/Documentation/block/data-integrity.txt @@ -246,7 +246,7 @@ will require extra work due to the application tag. retrieve the tag buffer using bio_integrity_get_tag(). -6.3 PASSING EXISTING INTEGRITY METADATA +5.3 PASSING EXISTING INTEGRITY METADATA Filesystems that either generate their own integrity metadata or are capable of transferring IMD from user space can use the @@ -283,7 +283,7 @@ will require extra work due to the application tag. integrity upon completion. -6.4 REGISTERING A BLOCK DEVICE AS CAPABLE OF EXCHANGING INTEGRITY +5.4 REGISTERING A BLOCK DEVICE AS CAPABLE OF EXCHANGING INTEGRITY METADATA To enable integrity exchange on a block device the gendisk must be diff --git a/Documentation/block/deadline-iosched.txt b/Documentation/block/deadline-iosched.txt index c23cab13c3d..72576769e0f 100644 --- a/Documentation/block/deadline-iosched.txt +++ b/Documentation/block/deadline-iosched.txt @@ -30,12 +30,18 @@ write_expire (in ms) Similar to read_expire mentioned above, but for writes. -fifo_batch +fifo_batch (number of requests) ---------- -When a read request expires its deadline, we must move some requests from -the sorted io scheduler list to the block device dispatch queue. fifo_batch -controls how many requests we move. +Requests are grouped into ``batches'' of a particular data direction (read or +write) which are serviced in increasing sector order. To limit extra seeking, +deadline expiries are only checked between batches. fifo_batch controls the +maximum number of requests per batch. + +This parameter tunes the balance between per-request latency and aggregate +throughput. When low latency is the primary concern, smaller is better (where +a value of 1 yields first-come first-served behaviour). Increasing fifo_batch +generally improves throughput, at the cost of latency variation. writes_starved (number of dispatches) |