Memory copy performance on G5

• Subject: Memory copy performance on G5
• From: Qingda Lu <email@hidden>
• Date: Mon, 7 Nov 2005 12:39:59 -0500
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I am new to the mac world, just started using a 2 ghz G5 cluster days ago.

I am doing something more than memory copy but I always start it with
understanding memory copy issues on the target architecture. I tried STREAM
benchmark on the G5 which gives 2GB/s copy bandwidth, while on an Intel
Xeon 2.4GHZ I got 4.5GB/S with SSE2 using non-temporal writes. G5 has a
theoretical memory bandwidth of 6.4 GB/s which is much higher than
2GB/s I got and also higher than the theoretical memory bandwidth of
that intel Xeon. I later tried to write my own copy routine using
Altivec, the performace was only improved a little. I tried memcpy and memmove, the result
is 3.1 GB/s, which is better but still less than half of 6.4GB/s.

Anyone has some idea about this? Is 3.1 the best I  can get. I am reading
bcopy.s in darwinsource/10.4.3/xnu-792.6.22/osfmk/ppc/. Is it the right file to look
at?

Thanks!

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