Messages in this thread | | | Date | Wed, 29 Jan 2014 19:32:04 +0100 | From | Oleg Nesterov <> | Subject | Re: Do we really need curr_target in signal_struct ? |
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On 01/29, Rakib Mullick wrote: > > On Wed, Jan 29, 2014 at 8:55 PM, Oleg Nesterov <oleg@redhat.com> wrote: > > On 01/29, Rakib Mullick wrote: > >> > >> On Tue, Jan 28, 2014 at 10:43 PM, Oleg Nesterov <oleg@redhat.com> wrote: > >> > > > >> AFAIU, ->current_target is only a loop breaker to avoid infinite loop, > > > > No. It caches the last result of "find a thread which can handle this > > group-wide signal". > > > The reason behind of my understanding is the following comments: > > /* > * No thread needs to be woken. > * Any eligible threads will see > * the signal in the queue soon. > */ > > What if, there's no thread in a group wants_signal()?
then complete_signal() returns without signal_wake_up().
> Or it can't > practically happen?
It can. Say, all threads has blocked this signal. And other reasons.
> >> but - by using while_each_thread() we can remove it completely, thus > >> helps to get rid from maintaining it too. > > > > ... and remove the optimization above. > > > >> I'll prepare a proper patch with you suggestions for reviewing. > > > > I am not sure we want this patch. Once again, I do not know how much > > ->curr_target helps, and certainaly it can't help always. But you > > should not blindly remove it just because yes, sure, it is not strictly > > needed to find a wants_signal() thread. > > > Are you thinking that , since things are not broken, then we shouldn't > try to do anything?
Hmm. No.
I am thinking that, since you misunderstood the purpose of ->curr_target, I should probably try to argue with your patch which blindly removes this optimization ?
I also think that this logic doesn't look perfect, but this is another story.
Oleg.
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