Matt Dillon writes:
>
> I modified my original C program again, this time to simply read
> the data from memory given a block size in kilobytes as an argument.
> I had to throw in a little __asm to do it right, but here are my results.
> It shows about 3.2 GBytes/sec from the L2 (well, insofar as my
> 3-instruction loop goes), and about 1.4 GBytes/sec from main memory.
>
>
> NOTE: cc x.c -O2 -o x
>
> ./x 4
> 3124.96 MBytes/sec (read)
<...>
> ./x 1024
> 1397.90 MBytes/sec (read)
>
> In contrast I get 1052.50 MBytes/sec on the Dell 2400 from the L2,
> and 444 MBytes/sec from main memory.
>
FWIW: 1.2GHz Athlon, VIA Apollo KT133 chipset, Asus A7V motherboard,
(PC133 ECC Registered Dimms)
./x 4
2393.70 MBytes/sec (read)
./x 8
2398.19 MBytes/sec (read)
<...>
./x 1024
627.32 MBytes/sec (read)
And a Dual 933MHz PIII SuperMicro 370DER Serverworks HE-SL Chipset
(2-way interleaved PC133 ECC Registered DIMMS)
./x 4
1853.54 MBytes/sec (read)
./x 1024
526.19 MBytes/sec (read)
There's something diabolic about your previous bw test, though. I
think it only hits one bank of interleaved ram. On the 370DER it gets
only 167MB/sec. Every other bw test I've run on the box shows copy
perf at around 260MB/sec (Hbench, lmbench). I see the same problem on
a PE4400 (also 2-way interleaved); it shows copy perf as 111MB/sec.
Every other test has it at 230MB/sec.
The Athlon copies at 174MB/sec, which is right about what lmbench, hbench,
etc, and your test show.
How's your P4 for floating point? Is real-life perf as good as the
specbench numbers would indicate, or do you need a better compiler
than GCC to get any benefit from it? My wife is a statistician, and
she runs some really fp intensive workloads. This Athlon is faster
than the Serverworks box and (barely) faster than a year-old Alpha
UP1000 for her code.
Drew
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