which function is instrumentable?

which function is instrumentable?

[Zhiwei Ying]

Hi,

I tried to trace down every function in a device driver, but it fails.
It may be cased too many instrumentation. But the problem is how can I
know which function is instrumentable and which is not? Or I have to
manually narrow the problem? Any idea?

Thanks,
Zhiwei

Error msg:
bad: scheduling from the idle thread!
Pid: 0, comm: swapper Tainted: G        W   2.6.35 #8
Call Trace:
 [<c102562d>] ? dequeue_task_idle+0x1d/0x30
 [<c102ae12>] ? dequeue_task+0x42/0x60
 [<c102ae4d>] ? deactivate_task+0x1d/0x30
 [<c14304ff>] ? schedule+0x25f/0x650
 [<c1432dd6>] ? apic_timer_interrupt+0x2a/0x30
 [<c16000d8>] ? addrconf_init+0x49/0x147
 [<c1001c61>] ? cpu_idle+0x51/0x70
 [<c15d48a7>] ? start_kernel+0x2c4/0x2ca
 [<c15d441f>] ? unknown_bootoption+0x0/0x192
bad: scheduling from the idle thread!
Pid: 0, comm: swapper Tainted: G        W   2.6.35 #8
Call Trace:
 [<c102562d>] ? dequeue_task_idle+0x1d/0x30
 [<c102ae12>] ? dequeue_task+0x42/0x60
 [<c102ae4d>] ? deactivate_task+0x1d/0x30
 [<c14304ff>] ? schedule+0x25f/0x650
 [<c1432dd6>] ? apic_timer_interrupt+0x2a/0x30
 [<c16000d8>] ? addrconf_init+0x49/0x147
 [<c1001c61>] ? cpu_idle+0x51/0x70
 [<c15d48a7>] ? start_kernel+0x2c4/0x2ca
 [<c15d441f>] ? unknown_bootoption+0x0/0x192

Re: which function is instrumentable?

[Adrien Kunysz]

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On Wed, Mar 23, 2011 at 09:22:12AM +0800, Zhiwei Ying wrote:
> I tried to trace down every function in a device driver, but it fails.
> It may be cased too many instrumentation. But the problem is how can I
> know which function is instrumentable and which is not? Or I have to
> manually narrow the problem? Any idea?

This

	$ stap -l 'module("foo").function("*")'

is supposed to give you a list of all the "probeable" functions in
module "foo".

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Re: which function is instrumentable?

[Zhiwei Ying]

I see. What I am looking for is to exclude those bad-function
automatically. I can write a script to test the function one by one,
but it's ugly.

Can stap provides some hint about the probability, which could be used
to estimate the correctness of instrumentation?

Can stap exclude those inlined function with some option?


On Wed, Mar 23, 2011 at 3:49 PM, Adrien Kunysz <adrien@kunysz.be> wrote:
> On Wed, Mar 23, 2011 at 09:22:12AM +0800, Zhiwei Ying wrote:
>> I tried to trace down every function in a device driver, but it fails.
>> It may be cased too many instrumentation. But the problem is how can I
>> know which function is instrumentable and which is not? Or I have to
>> manually narrow the problem? Any idea?
>
> This
>
>        $ stap -l 'module("foo").function("*")'
>
> is supposed to give you a list of all the "probeable" functions in
> module "foo".
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (GNU/Linux)
>
> iEYEARECAAYFAk2Jpf4ACgkQKLX03ZSPZGzLFgCfVPPsMNE0aP41dz4CbR4wvRgv
> dowAn2ZYglF0Y6jnbgHHzbyziYuWLtXM
> =TVHS
> -----END PGP SIGNATURE-----
>
>

Re: which function is instrumentable?

[William Cohen]

On 03/23/2011 04:23 AM, Zhiwei Ying wrote:
> I see. What I am looking for is to exclude those bad-function
> automatically. I can write a script to test the function one by one,
> but it's ugly.
> 
> Can stap provides some hint about the probability, which could be used
> to estimate the correctness of instrumentation?
> 
> Can stap exclude those inlined function with some option?
> 

The following will exclude the inlined functions:

stap -l 'module("foo").function("*").call'


-Will