From: "Ronciak, John" <john.ronciak@xxxxxxxxx>
Date: Mon, 6 Jun 2005 08:35:26 -0700
> We are dropping packets at the HW level (FIFO errors) with 256
> descriptors and the default weight of 64. As we said reducing the
> weight eliminates this which is understandable since the driver is being
> serviced more fequently. We also hacked the driver to do a buffer
> allocation per packet sent up the stack. This reduced the number of
> dropped pacekts by about 80% but it was still a significant number of
> drops (190K to 39K dropped). So I don't think this is where the problem
> is. This is also comfimed with the tg3 driver doing the buffer update
> to the HW every 25 descriptors.
I reach a different conclusion, sorry. :-)
Here is the invariant:
If you force the e1000 driver to do RX replenishment every N
packets it should reduce the packet drops the same (in the
single NIC case) as if you reduced the dev->weight to that
same value N.
You have two test cases, single NIC and multi-NIC, so you should
be very clear in which case your drop number applies to. They
are two totally different problems.
> We did not up the descriptor ring size with the default weight but will
> try this today and report back.
Thanks for all of your test data and hard work so far.
It's very valuable.
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