Re: [RFC PATCH 0/5] futex: introduce an optimistic spinning futex

* Waiman Long [off-list ref] wrote:

Testing done on a 4-socket Westmere-EX boxes with 40 cores (HT off) 
showed the following performance data (average kops/s) with various 
load factor (number of pause instructions) used in the critical 
section using an userspace mutex microbenchmark.

  Threads  Load	Waiting Futex	Spinning Futex 	  %Change
  -------  ----	-------------	--------------	  -------
    256	     1	     6894	    8883	    +29%
    256	    10	     3656	    4912	    +34%
    256	    50	     1332	    4358	   +227%
    256	   100	      792	    2753	   +248%
     10	     1	     6382	    4838	    -24%
     10	    10	     3614	    4748	    +31%
     10	    50	     1319	    3900	   +196%
     10	   100	      782	    2459	   +214%
      2	     1	     7905	    7194	   -9.0%
      2	    10	     4556	    4717	   +3.5%
      2	    50	     2191	    4167	    +90%
      2	   100	     1767	    2407	    +36%

So the numbers look interesting - but it would be _really_ important 
to provide noise/sttdev figures in a sixth column as well (denoted in 
percentage units, not in benchmark units), so that we know how 
significant a particular speedup (or slowdown) is.

Thanks,

	Ingo