[Beowulf] Intel buys QLogic InfiniBand business

Greg Lindahl lindahl at pbm.com
Sat Jan 28 00:29:36 EST 2012

On Fri, Jan 27, 2012 at 06:10:02PM -0800, Bill Broadley wrote:

> Anyone have an estimate on how much latency a direct connect to QPI
> would save vs pci-e?

~ 0.2us. Remember that the first 2 generations of InfiniPath were both
SDR: one for HyperTransport and one for PCIe. The difference was 0.3us
back then; PathScale + QLogic did some heroic things since to shorten
the pipeline stages & up the clock rate.

-- greg
(and if anyone needs a reminder, I no longer have any financial
involvement with QLogic or Intel.)

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