Hi, Here is the 4th version of the series to improve backup instances of the persistent ring buffer. The previous version is here:
https://lore.kernel.org/all/176828713313.2161268.62228177827727824.st...@mhiramat.tok.corp.google.com/ In this version, I added new fix [1/4] to reset last_boot_info when the ring buffer is reset. [2/4] is updated to allow resetting the readonly ring buffer via trace file. And [4/4] is adding a section for the backup instance to `debugging.rst`. Since backup instances are a kind of snapshot of the persistent ring buffer, it should be readonly. And if it is readonly there is no reason to keep it after reading all data via trace_pipe because the data has been consumed. But user should be able to remove the readonly instance by rmdir or truncating `trace` file. Thus, [2/3] makes backup instances readonly (not able to write any events, cleanup trace, change buffer size). Also, [3/3] removes the backup instance after consuming all data via trace_pipe. With this improvements, even if we makes a backup instance (using the same amount of memory of the persistent ring buffer), it will be removed after reading the data automatically. --- Masami Hiramatsu (Google) (4): tracing: Reset last_boot_info if ring buffer is reset tracing: Make the backup instance non-reusable tracing: Remove the backup instance automatically after read tracing/Documentation: Add a section about backup instance Documentation/trace/debugging.rst | 19 ++++ kernel/trace/trace.c | 164 ++++++++++++++++++++++++++++++------- kernel/trace/trace.h | 14 +++ kernel/trace/trace_boot.c | 5 + kernel/trace/trace_events.c | 68 +++++++++------ 5 files changed, 212 insertions(+), 58 deletions(-) -- Masami Hiramatsu (Google) <[email protected]>
