Re: [lwip-users] Automatic Rx DMA ring replenish

[Bill Auerbach]

Simon,

 

I commented based on the “This should improve performance” statement in Timmy’s message.  The intent was not to invalidate the change or deem it unnecessary, only to not have performance be a reason one heads off in the direction of adding this feature to their port.  I well could be wrong about performance too – this is merely an opinion based on code review.

 

Bill

 

From: address@hidden [mailto:address@hidden On Behalf Of Simon Goldschmidt
Sent: Thursday, November 03, 2011 9:47 AM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] Automatic Rx DMA ring replenish

 

"Bill Auerbach" <address@hidden>:

I haven’t benchmarked to be able to provide factual data, but I’ve done a lot of optimization and tweaking of lwIP to improve bandwidth and my study of pbufs and memory pools did not show the need for improvement considering all of the other things required to handle a TCP connection.

 

I saw the patch not as speed optimization but as a way to simplify the netif driver: to provide a robust implementation, a netif driver would have to ensure it retries if pbuf_alloc fails because the pool is empty (to prevent a deadlock). This patch prevents a netif driver having to implement some sort of timer because it just gets notified when pbufs are available again.

 

Simon