Date: Mon, 24 Feb 1997 11:27:26 -0800 From: "Jin Guojun[ITG]" <jin@george.lbl.gov> To: freebsd-hardware@freebsd.org, robsch@robkaos.ruhr.de Cc: skynyrd@opus.cts.cwu.edu Subject: Re: Memory speed of P6-200 (256k) Message-ID: <199702241927.LAA24844@george.lbl.gov>
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Message-1: } >> Not good :-). I have Triton-1 (ASUS P55TP4XE) with non-EDO RAM and the } >> benchmark runs at about 119.2MB/sec (1MB = 1048576). } } >Which BIOS are you using, and which revision of the motherboard? } } Award BIOS from about 1/1/96 and 2.4 motherboard. } } Bruce Message-2: } I found: } dd if=/dev/zero of=/dev/null bs=1m count=2000 } 2097152000 bytes transferred in 27.298230 secs (76823735 bytes/sec) } The motherboard is a P6NP5 (Natoma chipset) with 64 MB EDO-RAM. } The kernel is 3.0-current. } } Is this value normal for a P6-200? } If not, how can I speed it up? } } TIA } Robert I do not know what is the orginal messurement, but it looks very interesting. By invesgating such idea, I found that 2.1.x and 2.2 or higher have different memory sub-system or dd implementation. So, you guys should not worry any memory speed on your system, and there is no thing can change the speed beside change the memory sub-system, such as inteleaved memory system. The command "dd if=/dev/zero of=/dev/null bs=1m count=XXX" really does is to allocate 1MB memory and try to put zero into the piece of memory and repeat XXX times. Under 2.1.x-RELEASE, it looks like dd/memory-sub-system (more like dd) uses 4-bytes aligned register to memory operation, and 2.2/higher use 8-bytes aligned register to memory operation. I tested this operation under 6-different mortherboard and 4-different CPU speed. I have not compare the dd or memory sub-system between 2.1.x and 2.2/higher yet; but I am sure I got the right assumption. So, for these people want to know what is your best memory system performance, refer to ftp://george.lbl.gov/pub/ccs/performance.ps, page 6-8, and look for register to memory copy and memory copy. Do be comfused by this dd command :-) -Jin
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