[openib-general] [PATCH][3/7]ipoib performance patches -- remove tx_ring

[Shirley Ma]

Roland,

Roland Dreier <rdreier at cisco.com> wrote on 05/25/2006 09:24:01 AM:

> This also looks like a step backwards to me.  You are replacing a
> cache-friendly array with a cache-unfriendly linked list, which also
> requires two more lock/unlock operations in the fast path.

This patch reduces one extra ring between dev xmit queue and device 
send queue and removes tx_lock in completion handler.

The whole purpose to have the send_list and slock is for shutting down
clean up. Otherwise we don't need to maintain this list. And most likely 
when
shutting down, waiting for 5HZ, the list is empty. 

I could implment it differently, like use RCU list with cache-friendly. 
I thought it's not worth it before since i didn't see the gain.

Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638

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