Author: Jeremiah Penery
Date: 18:56:00 07/01/03
Go up one level in this thread
On June 30, 2003 at 16:04:07, Vincent Diepeveen wrote: >On June 29, 2003 at 23:44:42, Robert Hyatt wrote: > >>That's one I will wait to actually measure. I don't personally believe 40ns >>is doable, where current machines are hitting 120ns unless using registered >>DRAM. > >You are *not* hitting 120 ns. You need more like 380 ns for a *random* access >into the memory (like for example hashtable). The 120 ns is based upon >sequential stuff and as we both know chess is not like that. The exact technical >working i do not know 100% of the ram, but it is like this. it has some lines >opened. If you keep reasking from that same line then it is faster than when it >has to close it and reopen another. If you do a memory access on an already open page, to an open bank, you'll get something less than 75ns with any normal hardware today. On a completely random access on a 1cpu machine, you should not see more than 150ns. If you do, something is very wrong. >the access times of the dual Xeon as i measured them and dual MPs are more near >400 ns. Using my own software of course. i did some hard work there making >a bench. amazingly it is also pretty accurate at the x86 hardware. > >The fastest timings (no surprise) are single cpu solutions. Those go to around >280 ns to get a random lookup. Both P4 and K7s. Of course i didn't measure >overclocked stuff. > >the lookup in all cases is 8 bytes by the way. I just want to know *latency*. Your testing sucks.
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