[LU-9920] Use pagevec for marking pages dirty

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.13.0
• Severity: 3
• Assignee: Dongyang Li
• Reporter: Patrick Farrell

Description

When doing i/o from multiple writers to a single file, the
per-file page cache lock (mapping->tree_lock) becomes a
bottleneck.

Most current uses are single page at a time. This converts
one prominent use, marking page as dirty, to use a pagevec.

This improves shared file write performance notably when
many threads are writing to one file.

[NB: Detailed numbers coming. Looks like no change in
uncontended case, rising to ~25% for 8 writers.]

Issue Links

• is related to: LU-12429 Single client buffered SSF write is slower than O_DIRECT
• is related to: LU-9906 Allow Lustre page dropping to use pagevec_release
• is related to: LU-11775 buffered write single client improvements
• is related to: LU-11290 Batch callbacks in osc_page_gang_lookup