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pawn enumeration
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Ronald de Man



Joined: 28 Feb 2012
Posts: 840
PostPost subject: Re: price of complex indexing    Posted: Sat Jul 28, 2012 5:15 pm Reply to topic Reply with quote
syzygy wrote:
hgm wrote:
That is a lot, and seems much more than could be explained from the execution time of the few extra instructions. This suggests it actually decreases cache efficiency.

Well, one problem is that I did the transformation also in the main loop when looping over the table looking for work to do. When I loop through the table linearly, and do the reverse transformation before doing the work, things get a bit faster. Still, it is 10% slower.

A second problem is that my transformation might not sufficiently solve the problem, so I replaced (idx ^ (idx >> 12)) by (idx + (idx >> 12)) (with appropriate masking to make things work correctly). However, this only slows down things further.

I've measured cache-misses and they do indeed increase.

That was with "perf stat -e cache-misses".

Measuring just the number of L1 dcache misses shows that twisting of the index lowers the miss rate from 3.18% to 2.35% for KQRvKQ. However, this does not offset the extra computations.

Measuring LLC-loads and LLC-load-misses using perf seems to be broken.
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Subject Author Date/Time
pawn enumeration Daniel Shawul Tue Jul 24, 2012 1:23 am
      Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 1:36 am
            Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 2:06 am
                  Re: pawn enumeration Kevin Hearn Tue Jul 24, 2012 2:35 am
                        Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 3:01 am
                              Re: pawn enumeration Kevin Hearn Tue Jul 24, 2012 3:28 am
                                    Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 3:48 am
                                          Re: pawn enumeration Kevin Hearn Tue Jul 24, 2012 4:06 am
                                                Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 4:57 am
                  Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 4:57 pm
                        Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 6:55 pm
                  Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 7:01 pm
                        Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 9:47 pm
                              Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 10:47 pm
                                    Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 10:51 pm
                                          Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 11:00 pm
                                                Re: pawn enumeration Wylie Garvin Wed Jul 25, 2012 6:40 pm
                                                      Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 6:59 pm
                                                            Re: pawn enumeration Ronald de Man Wed Jul 25, 2012 7:22 pm
                                                                  Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 7:27 pm
                                                            Re: pawn enumeration Wylie Garvin Wed Jul 25, 2012 11:41 pm
                                                                  Re: pawn enumeration Ronald de Man Thu Jul 26, 2012 12:19 am
                                                                  Re: pawn enumeration Vincent Diepeveen Fri Jul 27, 2012 12:48 pm
                                                                        Re: pawn enumeration Ronald de Man Fri Jul 27, 2012 2:42 pm
                                                      Re: pawn enumeration Ronald de Man Wed Jul 25, 2012 7:21 pm
                                          Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 11:08 pm
                                                Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 11:22 pm
                                                      Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 11:39 pm
                                                      Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 11:39 pm
                                                            Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 12:08 am
      Related: malloc virtual Daniel Shawul Tue Jul 24, 2012 2:29 am
            Re: Related: malloc virtual Jon Dart Tue Jul 24, 2012 2:50 pm
                  Re: Related: malloc virtual Daniel Shawul Tue Jul 24, 2012 6:39 pm
                        Re: Related: malloc virtual Vincent Diepeveen Tue Jul 24, 2012 10:38 pm
                              Re: Related: malloc virtual Daniel Shawul Wed Jul 25, 2012 11:56 am
                                    Re: Related: malloc virtual Vincent Diepeveen Wed Jul 25, 2012 12:00 pm
                                          Re: Related: malloc virtual Daniel Shawul Wed Jul 25, 2012 12:06 pm
                                                Re: Related: malloc virtual Vincent Diepeveen Wed Jul 25, 2012 12:21 pm
                                                      Re: Related: malloc virtual Daniel Shawul Wed Jul 25, 2012 12:34 pm
                                                            Re: Related: malloc virtual Vincent Diepeveen Wed Jul 25, 2012 12:51 pm
      Re: pawn enumeration H.G.Muller Tue Jul 24, 2012 6:32 am
            Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 12:34 pm
            Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 4:31 pm
                  Re: pawn enumeration Daniel Shawul Tue Jul 24, 2012 9:29 pm
                        Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 10:22 pm
                              Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 11:01 pm
                                    Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 11:12 pm
                                          Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 11:32 pm
                                                Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 11:58 pm
                                                      Re: pawn enumeration Ronald de Man Wed Jul 25, 2012 1:04 am
                                                            Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 1:19 am
                        Re: pawn enumeration Ronald de Man Tue Jul 24, 2012 10:25 pm
                              Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 10:44 pm
                                    Re: pawn enumeration Daniel Shawul Wed Jul 25, 2012 12:08 pm
                                          Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 12:18 pm
                                                Re: pawn enumeration Daniel Shawul Wed Jul 25, 2012 12:30 pm
                                                      Re: pawn enumeration Vincent Diepeveen Wed Jul 25, 2012 12:43 pm
                                    Re: pawn enumeration Ronald de Man Wed Jul 25, 2012 6:58 pm
      Re: pawn enumeration Wylie Garvin Tue Jul 24, 2012 5:21 pm
            Re: pawn enumeration Vincent Diepeveen Tue Jul 24, 2012 5:26 pm
      price of complex indexing Daniel Shawul Fri Jul 27, 2012 1:24 pm
            Re: price of complex indexing Vincent Diepeveen Fri Jul 27, 2012 2:01 pm
                  Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 3:04 pm
                        Re: price of complex indexing Vincent Diepeveen Sun Jul 29, 2012 10:15 pm
                              Re: price of complex indexing Daniel Shawul Mon Jul 30, 2012 12:09 am
                                    Re: price of complex indexing Vincent Diepeveen Mon Jul 30, 2012 1:06 pm
                                          Re: price of complex indexing Daniel Shawul Mon Jul 30, 2012 1:45 pm
            Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 2:03 pm
                  Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 2:52 pm
                        Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 3:18 pm
                              Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 4:13 pm
                                    Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 9:46 pm
                                          Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 10:40 pm
                                                Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 10:52 pm
                                                      Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 11:10 pm
                                                            Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 11:53 pm
                                                                  Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 12:31 am
                                                                  Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 10:15 pm
                        Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 4:00 pm
                              Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 6:16 pm
                                    Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 9:47 pm
                                          Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 11:02 pm
                                                Re: price of complex indexing Ronald de Man Fri Jul 27, 2012 11:29 pm
                                                      Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 12:04 am
                                                            Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 1:00 am
                                                                  Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 1:15 am
                                                                  Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 1:30 am
                                                                  Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 1:59 am
                                                                        Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 2:48 am
                                                                              Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 3:21 am
                                                                                    Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 4:05 am
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 2:43 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 3:02 pm
                                                                  Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 2:39 am
                                                                        Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 3:37 am
                                                                              Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 2:49 pm
                        Re: price of complex indexing H.G.Muller Fri Jul 27, 2012 4:06 pm
                              Re: price of complex indexing Daniel Shawul Fri Jul 27, 2012 7:37 pm
                                    Re: price of complex indexing H.G.Muller Sat Jul 28, 2012 8:32 am
                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 1:20 pm
                                                Re: price of complex indexing H.G.Muller Sat Jul 28, 2012 1:40 pm
                                                      Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 2:10 pm
                              Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 12:27 am
                                    Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 11:42 am
                                          Re: price of complex indexing H.G.Muller Sat Jul 28, 2012 12:19 pm
                                                Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 1:39 pm
                                                      Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 2:04 pm
                                                            Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 3:11 pm
                                                                  Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 3:42 pm
                                                                  Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 3:46 pm
                                                                        Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 5:19 pm
                                                                              Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 5:22 pm
                                                                                    Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 5:34 pm
                                                                                          Cutoff rates Daniel Shawul Sat Jul 28, 2012 6:09 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 6:13 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 6:18 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 6:53 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 7:04 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 7:11 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 7:16 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 7:45 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 8:10 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 10:24 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 10:31 pm
                                                                                          Re: price of complex indexing Sven Schüle Sat Jul 28, 2012 10:46 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 10:53 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 11:23 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 11:39 pm
                                                                                          Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 11:50 pm
                                                                                          Re: price of complex indexing Daniel Shawul Sat Jul 28, 2012 11:54 pm
                                                      Re: price of complex indexing Ronald de Man Sat Jul 28, 2012 5:15 pm
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