[LU-4820] extra memcpy in read path

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0
• Affects Version/s: Lustre 2.4.1, Lustre 2.5.0, Lustre 2.6.0, Lustre 2.4.2, Lustre 2.5.1, Lustre 2.5.2, Lustre 2.4.3
• Labels: llnl
• Environment: ZFS
• Severity: 3
• Assignee: Alex Zhuravlev
• Reporter: Alex Zhuravlev

Description

osd_read_prep() in osd-zfs/ calls into dmu_read() which finds the buffers filled osd_bufs_get_read(). this is not needed and cost us extra memcpy() on all the reads.

Issue Links

• is related to: LU-5278 ZFS - many OST watchdogs with IOR