[LU-15223] Improve partial page read/write

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.12.0, Lustre 2.12.4
• Labels: arm arm-server ppc
• Environment: Arch: aarch64 (client)
• Severity: 3
• Assignee: Xinliang Liu
• Reporter: Xinliang Liu

Description

Currently, when the user issues a partial page read/write, Lustre (including client side and server side) will convert it into a full page read/write.

This is not efficient for small read/write operations , say if you want to read/write several bytes from a file, actually Lustre will  read/write a full page. This will become even worse for large PAGE_SIZE 64KB.

Make Lustre do a real partial page read/write which the read/write range is actual from start to end(which are given by the user), so that we can get an efficient small read/write.

Issue Links

• Clones: LU-11667 sanity test 317: FAIL: Expected Block 8 got 48 for f317.sanity
• is related to: LU-10300 Can the Lustre 2.10.x clients support 64K kernel page?