Messages in this thread | | | Date | Thu, 4 Mar 2021 09:11:42 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH] signal: Allow RT tasks to cache one sigqueue struct |
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On 2021-03-03 16:09:05 [-0600], Eric W. Biederman wrote: > Sebastian Andrzej Siewior <bigeasy@linutronix.de> writes: > > > From: Thomas Gleixner <tglx@linutronix.de> > > > > Allow realtime tasks to cache one sigqueue in task struct. This avoids an > > allocation which can increase the latency or fail. > > Ideally the sigqueue is cached after first successful delivery and will be > > available for next signal delivery. This works under the assumption that the RT > > task has never an unprocessed signal while a one is about to be queued. > > > > The caching is not used for SIGQUEUE_PREALLOC because this kind of sigqueue is > > handled differently (and not used for regular signal delivery). > > What part of this is about real time tasks? This allows any task > to cache a sigqueue entry.
It is limited to realtime tasks (SCHED_FIFO/RR/DL):
+static void __sigqueue_cache_or_free(struct sigqueue *q) +{ … + if (!task_is_realtime(current) || !sigqueue_add_cache(current, q)) + kmem_cache_free(sigqueue_cachep, q); +}
> Either the patch is buggy or the description is. Overall caching one > sigqueue entry doesn't look insane. But it would help to have a clear > description of what is going on.
Does this clear things up or is my logic somehow broken here?
> Eric
Sebastian
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