[Q] How to trace Kernel threads ??

[bokeron2020]

Hi.
I'm a total newbie with a problem.

My Defy has a bug, I believe. When the phone should be on suspend mode, a process called "suspend" starts using a lor of CPU time, so the battery lasts for just a few hours.

This is, I suppose, not the forum for asking for help about this, so I'll just say I've tried everything I could think of... and now I would like to use "strace" to... trace what's going on.

There are two problems.

One, the bug dissapears when the phone is suspended but connected to USB... so issuing commands is a problem without connection ... I suppose I could try WiFi, but I haven't tried yet.

Two. What I call the "suspend" process seems to be a kernel thread... so, I can't use strace.


Could someone, please, explain me wich command (if any) can help me trace the activity of this kernel thread ? Or... well, any other way you can think of.

 

[chaihg]

Good question and interesting one. Will wait for others to answer.

 

[Beach_Head]

You have strace compiled for Android?

Try issuing the command via ConnectBot or any other free terminal so you don't need to be connected via USB...

 

[bokeron2020]

That's part of the problem... I'm "hunting" a bug that only appears when the phone is suspended... If I use ConnectBot to write commands... the phone is, by definition, active. So...

Also... we have another problem: strace fails because "suspend" is not a process but a kernel thread... or that's what I've been told

 

[bokeron2020]

OK... I've finally been able to set up adb over wireless.

But strace doesn't work, and "top" shows that suspend almost always uses around 5%.

But... I still can't trace what suspend is doing.

 

[bokeron2020]

Would someone help me if I beg you on my knees ?

 

[fritolays]

Use the dalvik debugger, open command window and type ddms (assuming you have android sdk).
Once open under the Device menu you can see running process's/track them.

Heh didnt see that it doesnt happen when connected to usb. Dont know if ddms works over wifi too, should, but give it a shot.

 

[Beach_Head]

Why not just re-flash a stock SBF to get rid of the problem?

 

[bokeron2020]

Why not just re-flash a stock SBF to get rid of the problem?

Because, if it were that easy, the problem would have gone away sometime while flashing a sbf for the first 5 times...

Nope. It's either a bug or a hardware failure, I believe.

 

[martinml]

Use the dalvik debugger, open command window and type ddms (assuming you have android sdk).
Once open under the Device menu you can see running process's/track them

You can't track kernel threads via ddms. Only userland processes.

 

[adlx.xda]

You have strace compiled for Android?

Try issuing the command via ConnectBot or any other free terminal so you don't need to be connected via USB...

All adlxmod roms, starting from my first Cliq rom have strace

Sent from my Defy running adlxmod using Tapatalk

 

[bokeron2020]

All adlxmod roms, starting from my first Cliq rom have strace

Can you trace the "suspend" kernel thread ?

 

[bokeron2020]

Can you trace the "suspend" kernel thread ?

That was an easy question, wasn't it?

 

[martinml]

http://user-mode-linux.sourceforge.net/old/debugging.html
You can't because "(...) the kernel's threads are already being ptraced for system call interception, so gdb can't ptrace them"

Also, you could use KGDB, but it requires compiling your own kernel and a special setup, which is not possible in the Defy.