Date: Thu, 16 May 1996 09:09:12 +0600 (ESD) From: "Serge A. Babkin" <babkin@hq.icb.chel.su> To: hackers@freebsd.org Subject: EDO & Memory latency Message-ID: <199605160309.JAA29241@hq.icb.chel.su>
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I have just tried lmbench and the numbers it gives are looking slightly strange for me. It shows memory latency upto 500ns while I have 60-ns EDO memory in a Pentium/75 box. Okay, its external clock is 25MHz, this gives 40ns, one wait state, it gives another 40ns, it gives 80ns, but why the overhead is over 400ns ? Can it go from some VM subsystem activity ? I have 16M of RAM in my box and I runned lmbench with 8M maximal buffer size. The latency grows with the size of buffer. Is it possible that when the size of buffer grows the VM subsystem moves the non-recently used pages to some pool and when they are accessed again it gets the VM fault and remaps them back to that process? Thanks! -SB
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