Re: Question about bpf perfbuf/ringbuf: pinned in backend with overwriting

[Philo Lu <lulie@linux.alibaba.com>]

Thank you very much for your reply, making me understand ftrace buffer 
better.

I think it feasible to implement a new type of bpf map based on ftrace 
buffer. As for user interface, perhaps representing as files is still a 
good choice (like tracefs for ftrace)? But we should make sure that each 
map use a exclusive directory.

Also, I have tried relay map and submitted the patches [0], and any 
comment is welcome. Its behavior is exactly what I describe above. The 
buffer is represented as files in debugfs (`/sys/kernel/debug/`), one 
directory for one map. Users can get data with read or mmap interfaces.

The relay interface is also designed as a sub-buffer structure. It is 
light-weighted and provides users with much flexibility to formulate and 
process the data. Meanwhile, ftrace buffer provides thorough 
consideration for various use cases, so that users just care about the 
data entry by entry. It seems that ftrace buffer could be a better 
alternative of perfbuf. Therefore, I think it possible that relay and 
ftrace buffer coexist as bpf maps.

Wish you all happy holidays :)

[0]
https://lore.kernel.org/all/20231222122146.65519-1-lulie@linux.alibaba.com/