Re: opcontrol sh: write error: Invalid argument

On 01/28/2015 03:35 AM, Andrew Jones wrote:
>> Hi,
>>
>> Thanks for the output. The output above looks to match up with opcontrol do_param_setup():
>>
>> if test "$KERNEL_SUPPORT" = "yes" -a -f $MOUNT/backtrace_depth; then
>> set_param backtrace_depth $CALLGRAPH
>>
>> However, the "test yes = yes" doesn't match up with the verion I have. Which specific versions of the kernel and oprofile are you using. Do you have pointers to the specific sources for those?
>>
>> -Will

Hi Andrew,

What version of the kernel is being used on the target? Is it a new enough kernel to have perf support and allow the use of "operf -a" rather than opcontrol?
Using operf instead might avoid some of these issues with opcontrol.

> 
> Hi Will,
> 
> Sorry to double post.  I have a couple of bytes of extra info:
> 
> 1.  Regarding the "_sh: write error: Invalid Argument_" message:
> Jian Peng, in this post, appears to be having this exact same symptom:
> http://permalink.gmane.org/gmane.linux.oprofile/9406
> 
> Later on in that same thread, Maynard said that:
> "/OProfile should "work" in spite of the non-support of callgraph in the kernel./"
> 
> Question: Can I ignore that "Invalid argument" error?

Thanks for the pointer to the earlier email. Based on that it would be okay to comment out the write to /dev/oprofile/backtrace_depth.  However, if you have ability to rebuild the kernel the following patch to the kernel might be a better approach:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/mips/oprofile?id=1b48142a809ee03f48979fad647245dbe0ce423a

> 
> 
> 2. Regarding the "_Failed to exec opjitconv: No such file or directory_" message:
> In my daemon/init.c, opjitconv_path is equal to:
> /home/andrew/ex7/output/apps/oprofile_all/usr/bin//opjitconv  at runtime.
> 
> I guess this is derived from my --prefix.  If I ignore this error, I am still able to successfully do profiling anyway.  So is it safe to ignore this error too?
> 

The opjitconv is only needed for java code to map samples back to methods.  If you are not running java code then it will be safe to ignore that.  I know that space is premium, so maybe have a dummy opjitconv to quiet that error.

-Will
> 
> Thanks so much for your help!!!
> Regards,
> Andrew
> 


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