BM Seer Unofficial thoughts from an anonymous Sun employee

Huge Truthiness in IBM marketing

Wednesday May 23, 2007

Honestly I'd much rather blog about good news, talking about good products, good performance techniques and interesting new ways to look at how datacenters are evolving. But, when people look at the IBM announcements and the huge amounts of "truthiness" I just must point these things out.

OK let's look at this one:

    IBM states: "processor bandwidth of the Power6 chip - 300 gigabytes per second - could download the entire iTunes catalog in about 60 seconds"
The system must be fast, hey wait a minute that wasn't system bandwidth it was processor chip bandwidth. Was it peak or measured? Peak doesn't mean anything. What does it deliver as system-wide measured bandwidth? Could it really download (which means move it from here to there)?

This would all have been easy if IBM just published the easy-to-run STREAM benchmark, which IBM ran on all of the POWER5+ systems. (http://www.cs.virginia.edu/stream).

I'm also surprised that there were no 3.5GHz and 4.2GHz results published. Also given the range is the 4.7GHz a hot-house flower? It'll be interesting to see what they really ship in June 8.

IBM's marketing now seems to run on "Truthiness" :( so that means we'll have to keep showing the facts to keep things straight. I need to go off and wash my face now.

[2] Comments
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Posted at 06:06AM May 23, 2007 in IBM Follies
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IBM's 300 GB/sec bandwidth is the aggregate of the following:

L3 Cache to chip bandwidth = 80 GB/sec

I/O bus to chip bandwidth = 20 GB/sec

Main memory to chip bandwidth = 75 GB/sec

Chip to chip bandwidth (on book) = 80 GB/sec

Chip to chip bandwidth (off book) = 50 GB/sec

All numbers are address and data, bidirectional, and assume a 4.8 GHz to 5.0 GHz clock rate.

Posted by Mark on May 23, 2007 at 07:20 PM PDT #

One more thing. The 75 GB/sec of main memory bandwidth is likely only with the highest speed memory. From IT Jungle:

"The amount of main memory that customers can put in the new System p 570 server using the Power6 processor varies depending on the kind of DDR2 main memory customers use. Using slow 400 MHz DIMMs, main memory scales from 256 GB to 768 GB, but using faster 533 MHz DIMMs drops the capacity the box can hold by half. And using 667 MHz DIMMs cuts it in half again, to a maximum of 192 GB."

See: http://www.itjungle.com/breaking/bn052107-story02.html

Posted by Mark on May 23, 2007 at 07:25 PM PDT #

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