Re: [PATCH 2/4] e1000: add module option to set transmit descriptor size
From: Arthur Jones <hidden>
Date: 2008-06-27 14:55:15
Hi Jeff, ... On Fri, Jun 27, 2008 at 07:21:22AM -0700, Arthur Jones wrote:
On Thu, Jun 26, 2008 at 10:10:37PM -0700, Jeff Garzik wrote:quoted
Andy Gospodarek wrote:quoted
This patch added the TxDescPower parameter to the e1000 module. This parameter represents the size-order of each transmit descriptor. The valid size for descriptors would be 2^7 (128) - 2^12 (4096) bytes each. As this value decreases one may want to consider increasing the TxDescriptors value to maintain the same amount of frame memory. This patch does not change the defaults for any particular hardware model, so this will not have an effect on existing users.[...] I don't see why a module parameter is needed. In practice, nobody will ever think about this option, much less use it.
One thing that may not be immediately obvious is that setting the descriptor payload size low to avoid the chip bug has a very negative effect on performance. I don't want to lower the descriptor payload size unless I absolutely have to -- e.g. environments where link flap on chip reset causes major distruptions to the network... Arthur