From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Scott Wood <scottwood@freescale.com>,
linuxppc-dev@ozlabs.org, Timur Tabi <timur@freescale.com>
Subject: Re: [PATCH v5] introduce macro spin_event_timeout()
Date: Thu, 12 Mar 2009 08:49:50 +1100 [thread overview]
Message-ID: <1236808190.7086.61.camel@pasglop> (raw)
In-Reply-To: <fa686aa40903111010l7bd7e2f8r47c7d42184d0a36a@mail.gmail.com>
> No, not udelay. Or any delay for that matter. If spinning on a
> condition, then there is no advantage to burning cycles with a
> udelay(). Those cycles may as well be used to keep testing the
> condition so the loop can be exited faster. a udelay() would only
> serve to always make the busywait longer.
Well, there's a non-empty set of HW where polling as fast as you can
will effectively prevent it to make fwd progress...
Ben.
next prev parent reply other threads:[~2009-03-11 21:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-10 22:11 [PATCH v5] introduce macro spin_event_timeout() Timur Tabi
2009-03-10 22:33 ` Scott Wood
2009-03-10 22:37 ` Josh Boyer
2009-03-10 22:58 ` Scott Wood
2009-03-11 0:32 ` Josh Boyer
2009-03-10 23:59 ` Benjamin Herrenschmidt
2009-03-11 0:22 ` Timur Tabi
2009-03-11 0:24 ` Benjamin Herrenschmidt
2009-03-11 17:10 ` Grant Likely
2009-03-11 21:49 ` Benjamin Herrenschmidt [this message]
2009-03-11 21:54 ` Timur Tabi
2009-03-11 22:49 ` Scott Wood
2009-03-11 5:09 ` Roland Dreier
2009-03-11 16:31 ` Timur Tabi
2009-03-11 16:51 ` Scott Wood
2009-03-11 19:14 ` Timur Tabi
2009-03-11 19:22 ` Scott Wood
2009-03-11 20:45 ` Timur Tabi
2009-03-11 21:00 ` Scott Wood
2009-03-11 21:02 ` Timur Tabi
2009-03-11 21:03 ` Scott Wood
2009-03-11 0:44 ` Josh Boyer
2009-03-10 23:58 ` Benjamin Herrenschmidt
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