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Subject: Re: [RFC] New locking primitive for 2.5
From: Robert Love <rml@tech9.net>
To: Andrew Morton <akpm@zip.com.au>
Cc: Dave Hansen <haveblue@us.ibm.com>, Martin Wirth <Martin.Wirth@dlr.de>,
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On Thu, 2002-02-07 at 15:06, Andrew Morton wrote:

> A dynamic lock which says "we've spun for too long, let's sleep"
> seems to be a tradeoff between programmer effort and efficiency,
> and a bad one at that.

I'm not so sure.  What if we can't _know_ how long the lock will be held
because we don't know the status of the holder?  What if _he_ is
sleeping on some other lock or their are a lot of contending processes?

Certainly I agree, we need to put forth effort into designing things
right and with a minimal amount of lock held time.

> Possibly the locks could become more adaptive, and could, at
> each call site, "learn" the expected spintime.  But it all seems
> too baroque to me.

Agreed, this is much too much ;-)

	Robert Love

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