Subject: wireless: NETDEV_TX_LOCKED, use it or not?

From: Michael Buesch <[email-masked]>
Date: Sat, 19 Aug 2006 12:22:42 +0200

Hi,

I am currently wondering, if we should use NETDEV_TX_LOCKED
in the bcm43xx wireless net driver.

I currently don't have an SMP machine with a bcm43xx card
running, so I can't use benchmarks to find out.

There are various things to consider:
* The RX and TX-status paths, which also must take the spinlock
  aren't more expensive than on a normal Ethernet card (at least
  with d80211 stack).
* But the retry-path, when a NETDEV_TX_LOCKED is returned is
  slightly more expensive.

Well, the question is: Is it worth to return NETDEV_TX_LOCKED
on spinlock contention, or is it better to spin?
Is NETDEV_TX_LOCKED only desired on gigabit ethernet?

Thanks.

-- 
Greetings Michael.