Re: samples lost due to no permanent mapping and no file mapping

[John L. <joh...@ho...>]

On 07/28/20 17:00, William Cohen wrote:
>
> One though is how exactly are you starting doing the profiling?  Like the the following:
>
> operf <command_to_profile>
>
> Or attaching to a running process?
>
> operf --pid <pid>
>
> Or doing systemwide monitoring with --system-wide?

Thanks William,  my operf command is

operf --vmlinux /mnt/bullbild/linux-5.7.4-bullarch/vmlinux 
--session-dir=/tmp/oprof_session.200724_120854 --callgraph 
--separate-cpu --system-wide

so yes,  system-wide.
>
> You might check to see if the linux perf command has a similar problem with the quick spawn and death of processes.
> operf is using the same mechanism in the kernel to collect performance event samples.  There are some cases where the scanning of /proc can get behind the rapid creation and death of processes.  It would be useful to know if the problem lies with oprofile or is also seen in perf.
I will try with perf some time but have never used that before (did not 
know about it) so may be a little while getting to it.

Cheers,  John