Date: Tue, 07 May 1996 11:48:28 -0700 From: Wayne Scott <wscott@ichips.intel.com> To: asami@cs.berkeley.edu (Satoshi Asami) Cc: bde@zeta.org.au, current@freebsd.org, nisha@cs.berkeley.edu, marc@bowtie.nl, ken@area238.residence.gatech.edu, wollman@lcs.mit.edu, pattrsn@cs.berkeley.edu, culler@cs.berkeley.edu Subject: Re: more on fast bcopy Message-ID: <199605071845.LAA03457@ichips.intel.com> In-Reply-To: Your message of "Tue, 07 May 1996 06:06:09 PDT." <199605071306.GAA04277@silvia.HIP.Berkeley.EDU>
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> Yes, indeed, this is very interesting. I guess whatever I'm doing
> with all this is going to be moot once we all move to P6's. ;)
>
> By the way, I assume the external clock of the 200MHz P6 is 66MHz, is
> this correct? The memory copy speed of this machine seems to be
> slower than the Triton-based P5-133 that we have (see below). Do you
> know where the "B-step" Orion stands on the maturity curve, in terms
> of memory access speed?
The problem is that I gave you numbers on a lower performance desktop
machine.
On a high performance box with 4-way interleaved memory I get the
following:
size bandwidth
32 46.376812 MB/s
64 43.243243 MB/s yes this dip is expected
128 46.376812 MB/s
256 57.142857 MB/s
512 64.000000 MB/s
1024 66.666667 MB/s
2048 69.565217 MB/s
4096 69.565217 MB/s
8192 71.111111 MB/s
When I first ran then benchmark the results were toggling between
66 MB/s and 80 MB/s. The problem was that the benchmark is too fast for
gettimeofday to return accurate numbers. Increasing the size of the
buffer to be copied from 4 MBs to 32 MBs helpped alot. (For those
short on memory just put a loop around the calls to bcopy to make the
time longer.) I suspect this problem was occuring with luke's Pentium
number.
-Wayne
Wayne Scott MD6 Architecture
wscott@ichips.intel.com Work #: (503) 264-4165
Disclaimer: All views expressed are my own opinions, and not necessarily
those of Intel Corporation.
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