problem in run systemtap script

problem in run systemtap script

[ch huang]

how to handle this?
# cat exec.stp
probe module("ext3").function("*").call {
printf("%s -> %s\n", thread_indent(1), probefunc())
}
probe module("ext3").function("*").return {
printf("%s <- %s\n", thread_indent(-1), probefunc())
}


# stap exec.stp -o myout
WARNING: probe module("ext3").function("ext3_journalled_set_page_dirty@fs/ext3/inode.c:1780").call
(address 0xffffffff8804dff8) registration error (rc -22)
WARNING: probe module("ext3").function("bget_one@fs/ext3/inode.c:1419").call
(address 0xffffffff8804d50a) registration error (rc -22)
WARNING: probe module("ext3").function("bput_one@fs/ext3/inode.c:1425").call
(address 0xffffffff8804d511) registration error (rc -22)
WARNING: probe module("ext3").function("ext3_journalled_set_page_dirty@fs/ext3/inode.c:1780").return
(address 0xffffffff8804dff8) registration error (rc -22)
WARNING: probe module("ext3").function("bget_one@fs/ext3/inode.c:1419").return
(address 0xffffffff8804d50a) registration error (rc -22)
WARNING: probe module("ext3").function("bput_one@fs/ext3/inode.c:1425").return
(address 0xffffffff8804d511) registration error (rc -22)
ERROR: probe overhead exceeded threshold
WARNING: Number of errors: 1, skipped probes: 0
WARNING: /usr/local/bin/staprun exited with status: 1
Pass 5: run failed.  Try again with another '--vp 00001' option.

Re: problem in run systemtap script

[Frank Ch. Eigler]

ch huang <justlooks@gmail.com> writes:

> how to handle this?
> [...]
> WARNING: probe module("ext3").function("ext3_journalled_set_page_dirty@fs/ext3/inode.c:1780").call
> (address 0xffffffff8804dff8) registration error (rc -22)
> WARNING: probe module("ext3").function("bget_one@fs/ext3/inode.c:1419").call
> (address 0xffffffff8804d50a) registration error (rc -22)
> [...]

This could be the kernel kprobes limitation also mentioned in
<https://bugzilla.redhat.com/show_bug.cgi?id=801785>.  Some functions
will simply miss being probed.  But note that they are all warnings.

> ERROR: probe overhead exceeded threshold
> WARNING: Number of errors: 1, skipped probes: 0

This would be the real problem.  Rerun with -DSTP_NO_OVERLOAD to
disable the overload-prevention mechanism.

- FChE