Date: Tue, 6 Mar 2001 10:56:46 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Matt Dillon <dillon@earth.backplane.com> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Re: Machines are getting too damn fast Message-ID: <15013.2238.953211.516979@grasshopper.cs.duke.edu> In-Reply-To: <200103060013.f260DHY46910@earth.backplane.com> References: <Pine.BSF.4.32.0103051729350.84853-100000@mail.wolves.k12.mo.us> <200103060013.f260DHY46910@earth.backplane.com>
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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 ------------------------------------------------------------------------------ Andrew Gallatin, Sr Systems Programmer http://www.cs.duke.edu/~gallatin Duke University Email: gallatin@cs.duke.edu Department of Computer Science Phone: (919) 660-6590 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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