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cache alignment of tt
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Daniel Shawul



Joined: 14 Mar 2006
Posts: 2187
Location: Ethiopia
PostPost subject: Re: cache alignment of tt    Posted: Mon Mar 12, 2012 4:49 am Reply to topic Reply with quote
I was actually looking at the post you made sometime back comparing tt probes with and without alignment.
I was comparing nps of a 18 ply search since I didn't have a profiler but now I did QueryPerformanceCounter() and got a tiny tiny speed up BUT it still is slower nps wise when I take out the timing routine which is actually what I saw before.

Query performance of hash_probe 3 runs each

Code:

No alignment:

microsecond/probe         NPS
209989                         999109
210978                         998072
210551                        1000685

Alignment

206678                        1002805
206402                        1001222
205490                        1003311


That gives an improvement of 0.2% if you average the three runs but without the timing routing
Code:

Without alignment
1275611
1275611

With alignment
1262112
1263824

Now the one without alignment is faster. And the behavior is pretty consistent. It is also better to compare overall behavior but I really don't have any idea what is changing when I force the alignment.

Anyway it is not a very good optimization.

cheers
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Display posts from previous:   
Subject Author Date/Time
cache alignment of tt Daniel Shawul Sun Mar 11, 2012 10:22 pm
      Re: cache alignment of tt H.G.Muller Sun Mar 11, 2012 10:39 pm
            Re: cache alignment of tt Daniel Shawul Sun Mar 11, 2012 11:06 pm
      Re: cache alignment of tt Jon Dart Mon Mar 12, 2012 12:43 am
            Re: cache alignment of tt Daniel Shawul Mon Mar 12, 2012 2:53 am
            Re: cache alignment of tt Vincent Diepeveen Thu Mar 15, 2012 8:12 pm
      Re: cache alignment of tt Robert Purves Mon Mar 12, 2012 4:10 am
            Re: cache alignment of tt Daniel Shawul Mon Mar 12, 2012 4:49 am
      Re: cache alignment of tt Robert Hyatt Mon Mar 12, 2012 5:21 am
            Re: cache alignment of tt Ricardo Barreira Mon Mar 12, 2012 8:25 am
                  Re: cache alignment of tt Robert Hyatt Mon Mar 12, 2012 3:54 pm
                        Re: cache alignment of tt Alvaro Cardoso Tue Mar 13, 2012 12:33 am
                              Re: cache alignment of tt Robert Hyatt Thu Mar 15, 2012 2:15 pm
                                    Re: cache alignment of tt Rémi Coulom Thu Mar 15, 2012 4:42 pm
                                          Re: cache alignment of tt Robert Hyatt Thu Mar 15, 2012 5:03 pm
                                                Re: cache alignment of tt Daniel Shawul Thu Mar 15, 2012 5:08 pm
            Re: cache alignment of tt Daniel Shawul Mon Mar 12, 2012 12:49 pm
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