Re: Backward compatibility for insn probe point

[David Smith <dsmith@redhat.com>]

Maynard Johnson wrote:
> David Smith wrote:
>> Maynard Johnson wrote:

... stuff deleted ...

>>> The result of the above test is that the stap command hangs at
>>> "stapio:start_cmd:195 execing target_cmd /bin/ls".  If I Ctl-C the
>>> job, it finished (i.e, I see "Pass 5: run completed ..."), but the
>>> output file contents indicate the insn probe was not hit (i.e.,
>>> "itraced = 0").
>>>
>>> Any suggestions on where to look for the problem?
>> I took a look at this and fixed it.  For more details, see
> I've not tested the fix on x86 yet, but I'm afraid the results don't look right on ppc64/RHEL 5.
> But test results of 0.9.7 with your patch on ppc64/F11 were good -- no
regressions.  I used the
> following simple test script:

... script deleted ...

> I invoked the script as follows:
>      stap  -c /usr/bin/whoami simple-test.stp /usr/bin/whoami -o simple-out
> On Fedora 11, the simple-out file showed that I had nearly 330,000 insn probe hits.  On ppc64/RHEL
> 5.3, I had only 65 probe hits.  Can you try out the above script on an
x86/RHEL 5.3 system?

I've tested this on x86/RHEL5.3 (2.6.18-128.1.6.el5) and I get 226127
probe hits.  On x86_64/RHEL5.3 (2.6.18-128.1.6.el5) I get 198294 probe hits.

Off the top of my head that might mean there is a specific ppc64 utrace
problem.

Roland, do you know of any problems with original utrace doing
UTRACE_ACTION_SINGLESTEP on ppc64?

-- 
David Smith
dsmith@redhat.com
Red Hat
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