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Re: [RFC][PATCH][kprobe] enabling booster on the preemptible kernel, take 2
- From: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- To: "bibo,mao" <bibo_mao at linux dot intel dot com>
- Cc: "bibo,mao" <bibo dot mao at intel dot com>, "Keshavamurthy, Anil S" <anil dot s dot keshavamurthy at intel dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Prasanna S Panchamukhi <prasanna at in dot ibm dot com>, Ingo Molnar <mingo at redhat dot com>, SystemTAP <systemtap at sources dot redhat dot com>, Satoshi Oshima <soshima at redhat dot com>, Hideo Aoki <haoki at redhat dot com>, Yumiko Sugita <yumiko dot sugita dot yf at hitachi dot com>
- Date: Tue, 31 Oct 2006 22:17:15 +0900
- Subject: Re: [RFC][PATCH][kprobe] enabling booster on the preemptible kernel, take 2
- Organization: Systems Development Lab., Hitachi, Ltd., Japan
- References: <45338593.6090207@hitachi.com> <45459D94.8060905@intel.com> <454606EC.1030807@hitachi.com> <4546BCE7.9030008@linux.intel.com>
Hi bibo,
bibo,mao wrote:
>>> I do not know whether there exists non-freezeable and preemptive kernel
>>> thread, if there exist then this thread will not be frozen.
>>
>> In that case, freeze_processes() returns the positive value which
>> means how many processes are not frozen. If freeze_processes()
>> returns non-zero, this function aborts the garbage collection.
>>
> But from the code, return value of freeze_processes() represents how many
> processes can be frozen but are not frozen. I grep the kernel code, there
> still exists many processes which flag is PF_NOFREEZE.
> I think if current probed thread is PF_NOFREEZE, then kprobe_handler
> need skip the bootser.
OK, I see.
It seems problematic because the softirqd is PF_NOFREEZE and it
can execute most of functions...
I think we need to find a new way to solve this problem.
Thank you for your advice.
--
Masami HIRAMATSU
Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com