netdev - Re: [PATCH] qdisc: add tracepoint qdisc:qdisc

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Date:   Wed, 16 Aug 2017 14:09:47 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     brouer@...hat.com
Cc:     netdev@...r.kernel.org, pstaszewski@...are.pl
Subject: Re: [PATCH] qdisc: add tracepoint qdisc:qdisc_dequeue for dequeued
 SKBs

From: Jesper Dangaard Brouer <brouer@...hat.com>
Date: Tue, 15 Aug 2017 21:11:03 +0200

> The main purpose of this tracepoint is to monitor bulk dequeue
> in the network qdisc layer, as it cannot be deducted from the
> existing qdisc stats.
> 
> The txq_state can be used for determining the reason for zero packet
> dequeues, see enum netdev_queue_state_t.
> 
> Notice all packets doesn't necessary activate this tracepoint. As
> qdiscs with flag TCQ_F_CAN_BYPASS, can directly invoke
> sch_direct_xmit() when qdisc_qlen is zero.
> 
> Remember that perf record supports filters like:
> 
>  perf record -e qdisc:qdisc_dequeue \
>   --filter 'ifindex == 4 && (packets > 1 || txq_state > 0)'
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

I'll apply this to net-next, thanks Jesper.