Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] signal: Allow RT tasks to cache one sigqueue struct | Date | Thu, 04 Mar 2021 16:02:05 +0100 |
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On Thu, Mar 04 2021 at 09:11, Sebastian Andrzej Siewior wrote: > 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); > +}
We could of course do the caching unconditionally for all tasks.
Thanks,
tglx
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