From: Daniel Phillips <phillips@innominate.de>
To: Paul Cassella <pwc@sgi.com>, Tim Wright <timw@splhi.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] Semaphores used for daemon wakeup
Date: Fri, 22 Dec 2000 02:50:11 +0100 [thread overview]
Message-ID: <3A42B353.D0D249C1@innominate.de> (raw)
In-Reply-To: <3A42380B.6E9291D1@sgi.com> <Pine.SGI.3.96.1001221130859.8463C-100000@fsgi626.americas.sgi.com>
Paul Cassella wrote:
> The sync variable version of the dmabuf code snippet (assuming the
> dmabuf_mutex is never acquired from an interrupt) would look like this:
>
> dmabuf_init(...);
> {
> ...
> spin_lock_init(&dmabuf_spin);
> sv_init(&dmabuf_sv, &dmabuf_spin, SV_MON_SPIN);
> ...
> }
>
> dmabuf_alloc(...)
> {
>
> ...
> while (1) {
> spin_lock(&dmabuf_spin);
> attempt to grab a free buffer;
> if (success){
> spin_unlock(&dmabuf_spin);
> return;
> } else {
> sv_wait(&dmabuf_sv);
> }
> }
> }
>
> dmabuf_free(...)
> {
> ...
> spin_lock(&dmabuf_spin);
> free up buffer;
> sv_broadcast(&dmabuf_sv);
> spin_unlock(&dmabuf_spin);
> }
>
But isn't this actually a simple situation? How about:
dmabuf_alloc(...)
{
...
while (1) {
spin_lock(&dmabuf_lock);
attempt to grab a free buffer;
spin_unlock(&dmabuf_lock);
if (success)
return;
down(&dmabuf_wait);
}
}
dmabuf_free(...)
{
...
spin_lock(&dmabuf_lock);
free up buffer;
spin_unlock(&dmabuf_lock);
up(&dmabuf_wait);
}
--
Daniel
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next prev parent reply other threads:[~2000-12-22 2:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3A42380B.6E9291D1@sgi.com>
2000-12-21 19:30 ` [RFC] Semaphores used for daemon wakeup Paul Cassella
2000-12-21 22:19 ` Tim Wright
2000-12-22 1:12 ` Daniel Phillips
2000-12-22 1:50 ` Daniel Phillips [this message]
2000-12-22 4:26 ` Paul Cassella
2000-12-22 11:46 ` Daniel Phillips
2000-12-22 15:33 ` Tim Wright
2000-12-22 17:25 ` Daniel Phillips
2000-12-22 17:32 ` Brian Pomerantz
2000-12-17 12:06 Daniel Phillips
2000-12-19 0:14 ` Nigel Gamble
2000-12-19 3:34 ` Tim Wright
2000-12-19 13:11 ` Daniel Phillips
2000-12-19 16:07 ` Tim Wright
2000-12-20 1:34 ` Daniel Phillips
2000-12-21 16:28 ` Tim Wright
2000-12-19 9:01 ` Daniel Phillips
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