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Re: RFC: NAPI packet weighting patch

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: Re: RFC: NAPI packet weighting patch
From: "Michael Chan" <mchan@xxxxxxxxxxxx>
Date: Fri, 03 Jun 2005 12:49:29 -0700
Cc: mitch.a.williams@xxxxxxxxx, hadi@xxxxxxxxxx, john.ronciak@xxxxxxxxx, jdmason@xxxxxxxxxx, shemminger@xxxxxxxx, netdev@xxxxxxxxxxx, Robert.Olsson@xxxxxxxxxxx, ganesh.venkatesan@xxxxxxxxx, jesse.brandeburg@xxxxxxxxx
In-reply-to: <20050603.132922.63997492.davem@davemloft.net>
References: <20050603.120126.41874584.davem@davemloft.net> <Pine.CYG.4.58.0506031202280.3344@mawilli1-desk2.amr.corp.intel.com> <20050603.132257.23013342.davem@davemloft.net> <20050603.132922.63997492.davem@davemloft.net>
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On Fri, 2005-06-03 at 13:29 -0700, David S. Miller wrote:

> E1000 processes the full QUOTA of RX packets,
> _THEN_ replenishes with new RX buffers.  No wonder
> the chip runs out of RX descriptors.
> 
> You should replenish _AS_ you grab RX packets
> off the receive queue, just as tg3 does.

Yes, in tg3, rx buffers are replenished and put back into the ring as
completed packets are taken off the ring. But we don't tell the chip
about these new buffers until we get to the end of the loop, potentially
after a full quota of packets. Doesn't this make the end result the same
as e1000?


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