[LU-12550] automatic lockahead

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Assignee: Patrick Farrell
• Reporter: Patrick Farrell (Inactive)

Description

This is something Li Xi suggested a few years ago - It should be possible to do lockahead automatically by tracking the write pattern (like LU-12468) and using server-side contention checking to tell the client when to do this.  (Lockahead is currently only usable by clients which know to ask for it.)

This should let clients get good performance when strided writes with non-stripe aligned i/o, as long as the i/o is page aligned (LDLM & OSC locks are at page granularity).

Issue Links

• is related to: LU-12426 Add option to disable lock expansion on all requests
• is related to: LU-12468 Add writeahead state tracking
• is related to: LU-16939 ldlm: not expand the lock extent when the shared file is under lock contention
• is related to: LU-16964 I/O Path: Auto switch from BIO to DIO
• is related to: LU-13802 New i/o path: Buffered i/o as DIO
• is related to: LU-13805 i/o path: Unaligned direct i/o