This explained in great detail exactly why people are seeing the performance
they are from the P4 etc. The author knows his stuff.
http://www.emulators.com/pentium4.htm
Brandon
:-----Original Message-----
:From: [EMAIL PROTECTED]
:[mailto:[EMAIL PROTECTED]]On Behalf Of Kenneth D. Merry
:Sent: Tuesday, March 06, 2001 1:08 PM
:To: Andrew Gallatin
:Cc: Matt Dillon; [EMAIL PROTECTED]
:Subject: Re: Machines are getting too damn fast
:
:
:On Tue, Mar 06, 2001 at 10:56:46 -0500, Andrew Gallatin wrote:
:> 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)
:
:Dell Precision 420 (i840 chipset) with a single PIII 800 and probably one
:RIMM, unknown speed:
:
:{rivendell:/usr/home/ken/src:76:0} ./memspeed 4
:1049.51 MBytes/sec (read)
:{rivendell:/usr/home/ken/src:77:0} ./memspeed 1024
:378.41 MBytes/sec (read)
:
:The above machine may not have been completely idle, it seems a little
:slow.
:
:Dual 1GHz PIII SuperMicro 370DE6 Serverworks HE-SL chipset, 4x256MB PC133
:ECC Registered DIMMs:
:
:{gondolin:/usr/home/ken/src:51:0} ./memspeed 4
:1985.95 MBytes/sec (read)
:{gondolin:/usr/home/ken/src:52:0} ./memspeed 1024
:516.62 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 previous test showed about 270MB/sec on my Serverworks box:
:
:{gondolin:/usr/home/ken/src:53:0} ./memory_speed
:269.23 MBytes/sec (copy)
:
:Ken
:--
:Kenneth Merry
:[EMAIL PROTECTED]
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