From: Davidlohr Bueso <dave@stgolabs.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Greg KH <gregkh@linuxfoundation.org>,
"Luis R. Rodriguez" <mcgrof@kernel.org>,
mfuzzey@parkeon.com, "Eric W. Biederman" <ebiederm@xmission.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Daniel Wagner <wagi@monom.org>,
David Woodhouse <dwmw2@infradead.org>,
jewalt@lgsinnovations.com, rafal@milecki.pl,
Arend Van Spriel <arend.vanspriel@broadcom.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Li, Yi" <yi1.li@linux.intel.com>,
atull@kernel.org, Moritz Fischer <moritz.fischer@ettus.com>,
Petr Mladek <pmladek@suse.com>,
Johannes Berg <johannes.berg@intel.com>,
Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
"Coelho, Luciano" <luciano.coelho@intel.com>,
Kalle Valo <kvalo@codeaurora.org>, Andrew Lutomirski <luto@ker>
Subject: Re: [PATCH 2/4] swait: add the missing killable swaits
Date: Thu, 29 Jun 2017 11:33:39 -0700 [thread overview]
Message-ID: <20170629183339.GD3954@linux-80c1.suse> (raw)
In-Reply-To: <CA+55aFz=6XmH5MfwKLN6MZSyG8fAk-aD67mbDc1ZaKySzsq8aw@mail.gmail.com>
On Thu, 29 Jun 2017, Linus Torvalds wrote:
>So without some very compelling reason, I'd not want to add yet
>another wait-queue.
Yes, I was expecting this and very much agree.
I'll actually take a look at wake_q for wake_up_all() and co. to see if
we can reduce the spinlock hold times. Of course it would only make sense
for more than a one wakeup.
>I actually think swait is pure garbage. Most users only wake up one
>process anyway, and using swait for that is stupid. If you only wake
>up one, you might as well just have a single process pointer, not a
>wait list at all, and then use "wake_up_process()".
But you still need the notion of a queue, even if you wake one task
at a time... I'm probably missing your point here.
>There is *one* single user of swake_up_all(), and that one looks like
>bogus crap also: it does it outside of the spinlock that could have
>been used to protect the queue - p,lus I'm not sure there's really a
>queue anyway, since I think it's just the grace-period kthread that is
>there.
So those cases when there's only one waiter I completely agree should
not be using waitqueues. pcpu-rwsems in the past suffered from this.
Thanks,
Davidlohr
next prev parent reply other threads:[~2017-06-29 18:33 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-14 22:20 [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 1/4] test_firmware: add test case for SIGCHLD on sync fallback Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 2/4] swait: add the missing killable swaits Luis R. Rodriguez
[not found] ` <20170614222017.14653-3-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-29 12:54 ` Greg KH
[not found] ` <20170629125402.GH26046-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 13:05 ` Thomas Gleixner
2017-06-29 13:35 ` Greg KH
2017-06-29 13:46 ` Thomas Gleixner
2017-06-29 16:13 ` Linus Torvalds
2017-06-29 16:31 ` Matthew Wilcox
2017-06-29 17:29 ` Luis R. Rodriguez
2017-06-29 17:40 ` Davidlohr Bueso
2017-06-29 17:57 ` Linus Torvalds
2017-06-29 18:33 ` Davidlohr Bueso [this message]
[not found] ` <20170629183339.GD3954-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-06-29 18:59 ` Linus Torvalds
[not found] ` <CA+55aFz8Mhx+A-g-5yOG-O1ZLRUR_fpeeA4iBNGH8EnDBZEdpA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-06-29 19:40 ` Luis R. Rodriguez
2017-06-29 19:44 ` Luis R. Rodriguez
[not found] ` <20170629194455.GR21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:58 ` Jakub Kicinski
2017-06-29 22:50 ` Luis R. Rodriguez
2017-06-29 22:53 ` Jakub Kicinski
2017-06-29 23:00 ` Luis R. Rodriguez
2017-06-29 23:06 ` Jakub Kicinski
[not found] ` <20170629225003.GU21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-07-12 21:33 ` Luis R. Rodriguez
[not found] ` <20170629194015.GQ21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:57 ` Linus Torvalds
2017-07-05 2:06 ` Davidlohr Bueso
[not found] ` <20170705020635.GD11168-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-07-07 19:58 ` Linus Torvalds
2017-07-07 22:27 ` Davidlohr Bueso
2017-07-07 22:48 ` Linus Torvalds
2017-06-29 19:15 ` Marcelo Tosatti
[not found] ` <20170629191506.GB12368-I4X2Mt4zSy4@public.gmane.org>
2017-06-30 4:03 ` Linus Torvalds
2017-06-30 11:55 ` Marcelo Tosatti
2017-06-30 11:57 ` Marcelo Tosatti
2017-06-30 17:30 ` Krister Johansen
2017-06-14 22:20 ` [PATCH 3/4] firmware: avoid invalid fallback aborts by using killable swait Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 4/4] firmware: send -EINTR on signal abort on fallback mechanism Luis R. Rodriguez
2017-06-15 7:49 ` [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Martin Fuzzey
[not found] ` <20170614222017.14653-1-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-26 21:19 ` Luis R. Rodriguez
2017-06-29 15:14 ` Greg KH
[not found] ` <20170629151442.GA4880-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 17:29 ` Luis R. Rodriguez
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