Subject: [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro

From: [email-masked] (Timur Tabi)
Date: Wed, 31 Jul 2013 19:13:02 -0500

On 07/31/2013 07:04 PM, Stephen Boyd wrote:
> If it yields why are we using udelay? Why not usleep_range()? It would
> be useful to have a variant that worked in interrupt context and it
> looked like that was almost possible.

I've never heard of usleep_range() before, so I don't know if it
applies.  Apparently, udelay() includes its own call to cpu_relax().  Is
it possible that cpu_relax() is a "lightweight" yield, compared to sleeping?

FYI, you might want to look at the code reviews for spin_event_timeout()
on the linuxppc-dev mailing list, back in March 2009.

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Timur Tabi