Re: [HELP] Systemtap fails to load kernel module

[fche at redhat dot com (Frank Ch. Eigler)]

Hi, Jovi -

jovi wrote:

> [...]  I found one workaround is decrease the value of
> /proc/sys/vm/min_free_kbytes, it works, but it's still a workaround,
> and it's annoying to change that value again and again.

We could put such logic into staprun perhaps - to try to empty out a
bit of kernel memory just before loading the module.


> We also tried to use bulk mode in systemtap, it eliminated the
> memory allocation error, but the retrieved output is unreadable, so
> we discard the bulk mode.

One uses the stap_merge script to combine the per-cpu output files
into a single readable file.


> Note that there have a lot of free memory in system, it's not
> because of out of memory, it's memory fragmentation.

Have you experimented with a smaller "stap -s1"?  (Maybe we could
support fractions-of-megabytes.)  Or maybe we are using an
unnecessarily fragmentation-sensitive allocation machinery in that
part of the runtime code.

- FChE