Re: [RFC] HOWTO use NAPI to reduce TX interrupts

From: David Miller
Date: Mon Aug 21 2006 - 20:29:34 EST

From: Roland Dreier <rdreier@xxxxxxxxx>
Date: Mon, 21 Aug 2006 17:29:05 -0700

> This is a digression from spidernet, but what if a device is able to
> generate separate MSIs for TX and RX? Some people from IBM have
> suggested that it is beneficial for throughput to handle TX work and
> RX work for IP-over-InfiniBand in parallel on separate CPUs, and
> handling everything through the ->poll() method would defeat this.

The TX work is so incredibly cheap, relatively speaking, compared
to the full input packet processing path that the RX side runs
that I see no real benefit.

In fact, you might even get better locality due to the way the
locking can be performed if TX reclaim runs inside of ->poll()
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