Re: [Dle-develop] [PATCH tracing/kprobes] kprobes: Disable booster when CONFIG_PREEMPT=y

[Masami H. <mhi...@re...>]

Ingo Molnar wrote:
> 
> * Masami Hiramatsu <mhi...@re...> wrote:
> 
>> Disable kprobe booster when CONFIG_PREEMPT=y, because it can't ensure that 
>> all kernel threads preempted on kprobe's boosted slot run out from the slot 
>> even using freeze_processes().
> 
> hm, this really sucks as it makes preemptible kernels perform worse. Is there 
> no better solution?
> 
>> The booster on preemptive kernel will be resumed if synchronize_tasks() or 
>> something like that is introduced.
> 
> such as this one?

Yes, I think this synchronize_tasks(), which just (sleeping) wait until
all currently preempted tasks are wake up and scheduled, can ensure safety.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhi...@re...