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Re: [PATCH 1/6] Optimize number of accesses to *adapt_count in lock elision code.


Dominik Vogt <vogt@linux.vnet.ibm.com> writes:

> The changes to the original patches before 2.18 led to semantical changes of
> the adapt_count argument.  In the current code, *adapt_count cannot fall below
> zero.  When elision is attempted, *adapt_count is always exactly zero.  This
> fact can be exploited to reduce the number of accesses to *adapt_count and to
> simplify updating *adapt_count.

First in hardware <= is exactly the same performance as == 

I don't think the > 0 changes are correct. Previously it was a edge
trigger, you made it a level trigger, which is very different.

Also the compiler takes care of CSEing anyways, no need to 
do it manually.

Nack.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only


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