From: Sean Hefty <sean.hefty@intel.com>
Date: Mon, 4 Jun 2012 21:51:41 +0000 (-0700)
Subject: rsocket: Spin before blocking on an rsocket
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=abeec3639c7cc2d1acf195e33d1eb7e3bff91ebc;p=~shefty%2Flibrdmacm.git

rsocket: Spin before blocking on an rsocket

The latency cost of blocking is significant compared to round
trip ping-pong time.  Spin briefly on rsockets before calling
into the kernel and blocking.

We calculate the time to delay blocking by timing the round
trip ping-pong time on a QP configured for loopback traffic.  The
delay time is a multiple of this time to include wire transfer
time, plus minimal response time on the remote side.

As a completely unintentional side effect, this just happens to
improve application performance in benchmarks, like netpipe.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
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