The patch needs an ack, probably I just misunderstood the comments.
Suppose that the main thread blocks the signal. In that case
__group_complete_signal() tries to find another thread starting from
signal->curr_target.
The comment says about load-balancing, but this is not what happens?
Suppose that wants_signal(signal->curr_target) == T. In that case we
always choose the same ->curr_target thread. Isn't it better to try
to "spread" the signals over the thread group?
With this patch we are trying to find another suitable thread starting
from next_thread(signal->curr_target), thus distributing the load over
the whole thread group.
Bad idea? If not, probably we can also remove the "if (wants_signal())"
at the top of __group_complete_signal() ?
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 25/kernel/signal.c~4_GCS_BALANCE 2008-03-06 01:07:55.000000000 +0300
+++ 25/kernel/signal.c 2008-03-06 01:34:57.000000000 +0300
@@ -863,13 +863,14 @@ __group_complete_signal(int sig, struct
/*
* Otherwise try to find a suitable thread.
*/
- t = signal->curr_target;
- if (t == NULL)
- /* restart balancing at this thread */
- t = signal->curr_target = p;
+ if (!signal->curr_target)
+ signal->curr_target = p;
- while (!wants_signal(sig, t)) {
+ for (t = signal->curr_target ;; ) {
t = next_thread(t);
+ if (wants_signal(sig, t))
+ break;
+
if (t == signal->curr_target)
/*
* No thread needs to be woken.
--
