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Re: Backward compatibility for insn probe point
- From: David Smith <dsmith at redhat dot com>
- To: Maynard Johnson <maynardj at us dot ibm dot com>
- Cc: systemtap at sourceware dot org, "Frank Ch. Eigler" <fche at redhat dot com>, Roland McGrath <roland at redhat dot com>
- Date: Thu, 30 Apr 2009 12:59:57 -0500
- Subject: Re: Backward compatibility for insn probe point
- References: <49D3E3DF.1000108@us.ibm.com> <49F61D09.8090503@redhat.com> <49F8C1C0.8070208@us.ibm.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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