[LU-14428] Convert tracefile to use ring_buffer from linux

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Assignee: Neil Brown
• Reporter: Neil Brown

Description

Linux contains a ring_buffer which supports low-overhead appends for messages.

This is similar to the trace log in tracefile.c, but with lower overhead.

Converting to use this removes a lot of code and reduces duplication for when we merge lustre upstream.

 

Issue Links

• has to be done before: LU-16746 Convert tracefile to export debug logs via character device
• is related to: LU-17418 Lustre crashed immediately after load with debug kernel
• is related to: LU-15306 recovery-small: lightweight client was not recovered
• is related to: LU-8980 Add tracepoint support to Lustre
• is related to: LU-9859 libcfs simplification