Re: [RFC] lin-lwp.c prelim changes for new thread model

[Andrew Cagney <ac131313@redhat.com>]

>> The minimal change I propose below is as follows:
>> When we send kill(SIGSTOP) to all the threads, we now include
>> the event thread, where previously we had made him a special case.
>> That way, whether in the new model or the old one, we can now do
>> a waitpid on every thread including the event thread.
>> 
>> What do you think?
> 
> 
> To be honest, I don't like this very much.  You're hurting performance
> in the current case (whose performance is already quite bad enough,
> thank you!).  I don't think that the additional complexity/waiting is
> worthwhile.

Just an aside,

At present GDB does ~60 system calls per multi-threaded single step (see 
previous discussion related to ptrace), these extra two calls may easily 
prove to be in the noise.  Given the thread has already stopped, they 
should be close to kernel no-ops.

When commenting on performance, the thing that is always needed is hard 
data either supporting or dismissing any claim.

Andrew