Re: [RFC PATCH] net: add additional lock to qdisc to increase enqueue/dequeue fairness

David Miller
2010-03-23T21:44:50Z

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 23 Mar 2010 21:54:27 +0100

> Quite frankly, the real problem in this case is not the reduced
> throughput, but fact that one cpu can stay a long time doing the xmits
> to device, of skb queued by other cpus. This can hurt latencies a lot,
> for real time threads for example...
>
> I wonder if ticket spinlocks are not the problem. Maybe we want a
> variant of spinlocks, so that cpu doing transmits can get the lock
> before other cpus...

I want to note that things operate the way they do now
intentionally.

Herbert Xu and Jamal Hadi Salim were active in this area
about 4 years ago.