From: Till Straumann <strauman@slac.stanford.edu>
To: Josh Cartwright <josh.cartwright@ni.com>
Cc: "linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: How to unblock a thread from a hard isr (IRQF_NO_THREAD)
Date: Thu, 08 Nov 2012 22:50:28 -0600 [thread overview]
Message-ID: <509C8B94.2030906@slac.stanford.edu> (raw)
In-Reply-To: <20121109044237.GE1718@beefymiracle.amer.corp.natinst.com>
On 11/08/2012 10:42 PM, Josh Cartwright wrote:
> On Thu, Nov 08, 2012 at 10:28:53PM -0600, Till Straumann wrote:
>> Thanks, that's helpful.
>>
>> Wouldn't it also be possible to make my own version of
>> prepare_to_wait()/finish_wait()/wake_up() etc. which internally
>> use a raw spinlock instead of a normal one?
> I believe that what you described used to exist in the form of a
> 'simple' waitqueue, but I don't recall what happened to it. Maybe
> Thomas can shed some light here.
>
> In general though, if you care about determinism, you'd want to avoid
> the use of such a mechanism unless you can somehow externally provide an
> upper bound on the number of waiters.
>
> Josh
Of course. However, for the type of synchronization device we are talking
about here (hardirq wakes up a user-land worker) a (hardirq-safe)
completion-like
device supporting a single waiter only would be good enough.
- Till
prev parent reply other threads:[~2012-11-09 4:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-08 22:28 How to unblock a thread from a hard isr (IRQF_NO_THREAD) Till Straumann
2012-11-08 23:12 ` Tim Sander
2012-11-09 0:53 ` Till Straumann
[not found] ` <201211091518.36344.tim01@vlsi.informatik.tu-darmstadt.de>
2012-11-09 17:27 ` Till Straumann
2012-11-09 4:08 ` Josh Cartwright
2012-11-09 4:28 ` Till Straumann
2012-11-09 4:42 ` Josh Cartwright
2012-11-09 4:50 ` Till Straumann [this message]
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