netdev - Re: [net-next PATCH 03/15] net: sched: remove remaining uses for qdisc

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Date:   Tue, 23 Aug 2016 14:10:45 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     jhs@...atatu.com, davem@...emloft.net, brouer@...hat.com,
        xiyou.wangcong@...il.com, alexei.starovoitov@...il.com,
        john.r.fastabend@...el.com, netdev@...r.kernel.org
Subject: Re: [net-next PATCH 03/15] net: sched: remove remaining uses for
 qdisc_qlen in xmit path

On Tue, 2016-08-23 at 13:23 -0700, John Fastabend wrote:
> sch_direct_xmit() uses qdisc_qlen as a return value but all call sites
> of the routine only check if it is zero or not. Simplify the logic so
> that we don't need to return an actual queue length value.
> 
> This introduces a case now where sch_direct_xmit would have returned
> a qlen of zero but now it returns true. However in this case all
> call sites of sch_direct_xmit will implement a dequeue() and get
> a null skb and abort. This trades tracking qlen in the hotpath for
> an extra dequeue operation. Overall this seems to be good for
> performance.
> 
> Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>