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Re: registration error (rc -84) and -DSTP_OVERLOAD_THRESHOLD
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: mglt dot biz at gmail dot com
- Cc: systemtap at sourceware dot org
- Date: Wed, 01 Jun 2011 09:37:31 -0400
- Subject: Re: registration error (rc -84) and -DSTP_OVERLOAD_THRESHOLD
- References: <4DE5EEEA.7070400@gmail.com>
mglt.biz wrote:
> [...] While running my tap script, I receive WARNINGs and would
> like to knwo how to consider them. [...]
> WARNING: probe
> kernel.function("tcp_new_space@net/ipv4/tcp_input.c:4885") (address
> 0xffffffff814064f0) registration error (rc -84)
This is an error (-EILSEQ) that comes from the kernel, most likely
arch/x86/kernel/kprobes.c. It may be a somehow blacklisted function,
or perhaps a problem with the 'optimized kprobes' widget. It may help
to get a vmlinux disassembly around that 0xffffffff814064f0 address.
> How does it really impact the probe? For exmaple, does a probe on
> tcp_new_space for example don't consider the function ?
That's correct, such a probe will just not be activated, and its
handler never run.
> By the way, I also noticed some problems with the
> -DSTP_OVERLOAD_THRESHOLD. The script does not run and sometime it
> may result by frezzing the OS. We don't have any problems with the
> -DSTP_NO_OVERLOAD option for example. [...]
We'd probably need some more details. Mis-set THRESHOLD type values
should do no worse than abort the script prematurely. Try
# stap -t -v
Share the script and its invocation.
- FChE