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Re: RFC: NAPI packet weighting patch

To: jdmason@xxxxxxxxxx
Subject: Re: RFC: NAPI packet weighting patch
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Thu, 02 Jun 2005 15:12:12 -0700 (PDT)
Cc: shemminger@xxxxxxxx, john.ronciak@xxxxxxxxx, hadi@xxxxxxxxxx, mitch.a.williams@xxxxxxxxx, netdev@xxxxxxxxxxx, Robert.Olsson@xxxxxxxxxxx, ganesh.venkatesan@xxxxxxxxx, jesse.brandeburg@xxxxxxxxx
In-reply-to: <200506021651.49013.jdmason@xxxxxxxxxx>
References: <468F3FDA28AA87429AD807992E22D07E0450BFD0@orsmsx408> <20050602143126.7c302cfd@xxxxxxxxxxxxxxxxx> <200506021651.49013.jdmason@xxxxxxxxxx>
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From: Jon Mason <jdmason@xxxxxxxxxx>
Date: Thu, 2 Jun 2005 16:51:48 -0500

> Why not have the driver set the weight to 16/32 respectively for the
> weight (or better yet, have someone run numbers to find weight that
> are closer to what the adapter can actually use)?  While these
> numbers may not be optimal for every system, this is much better
> that the current system, and would only require 5 or so extra lines
> of code per NAPI enabled driver.

Why do this when we can adjust the weight in one spot,
namely the upper level NAPI ->poll() running loop?

It can measure the overhead, how many packets processed, etc.
and make intelligent decisions based upon that.  This is a CPU
speed, memory speed, I/O bus speed, and link speed agnostic
solution.

The driver need not take any part in this, and the scheme will
dynamically adjust to resource usage changes in the system.

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