Loopback and Nagle's algorithm

From: Adam McLaurin
Date: Mon Apr 11 2011 - 22:38:14 EST


I understand that disabling Nagle's algorithm via TCP_NODELAY will
generally degrade throughput. However, in my scenario (150 byte
messages, sending as fast as possible), the actual throughput penalty
over the network is marginal (maybe 10% at most).

However, when I disable Nagle's algorithm when connecting over loopback,
the performance hit is *huge* - 10x reduction in throughput.

The question is, why is disabling Nagle's algorithm on loopback so much
worse w.r.t. throughput? Is there anything I can do to reduce the
incurred throughput penalty?

Thanks,
Adam
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