From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rick Jones <rick.jones2@hpe.com>,
netdev@vger.kernel.org, brouer@redhat.com
Subject: Re: Netperf UDP issue with connected sockets
Date: Thu, 17 Nov 2016 14:42:48 +0100 [thread overview]
Message-ID: <20161117144248.23500001@redhat.com> (raw)
In-Reply-To: <1479388850.8455.240.camel@edumazet-glaptop3.roam.corp.google.com>
On Thu, 17 Nov 2016 05:20:50 -0800
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2016-11-17 at 09:16 +0100, Jesper Dangaard Brouer wrote:
>
> >
> > I noticed there is a Send-Q, and the perf-top2 is _raw_spin_lock, which
> > looks like it comes from __dev_queue_xmit(), but we know from
> > experience that this stall is actually caused by writing the
> > tailptr/doorbell in the HW. Thus, this could benefit a lot from
> > bulk/xmit_more into the qdisc layer.
>
> The Send-Q is there because of TX-completions being delayed a bit,
> because of IRQ mitigation.
>
> (ethtool -c eth0)
>
> It happens even if you do not have a qdisc in the first place.
>
> And we do have xmit_more in the qdisc layer already.
I can see that qdisc layer does not activate xmit_more in this case.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
$ ethtool -c mlx5p4
Coalesce parameters for mlx5p4:
Adaptive RX: on TX: off
stats-block-usecs: 0
sample-interval: 0
pkt-rate-low: 0
pkt-rate-high: 0
rx-usecs: 3
rx-frames: 32
rx-usecs-irq: 0
rx-frames-irq: 0
tx-usecs: 16
tx-frames: 32
tx-usecs-irq: 0
tx-frames-irq: 0
rx-usecs-low: 0
rx-frame-low: 0
tx-usecs-low: 0
tx-frame-low: 0
rx-usecs-high: 0
rx-frame-high: 0
tx-usecs-high: 0
tx-frame-high: 0
next prev parent reply other threads:[~2016-11-17 17:18 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-03 14:59 High perf top ip_idents_reserve doing netperf UDP_STREAM Jesper Dangaard Brouer
2014-09-03 15:17 ` Eric Dumazet
2016-11-16 12:16 ` Netperf UDP issue with connected sockets Jesper Dangaard Brouer
2016-11-16 17:46 ` Rick Jones
2016-11-16 22:40 ` Jesper Dangaard Brouer
2016-11-16 22:50 ` Rick Jones
2016-11-17 0:34 ` Eric Dumazet
2016-11-17 8:16 ` Jesper Dangaard Brouer
2016-11-17 13:20 ` Eric Dumazet
2016-11-17 13:42 ` Jesper Dangaard Brouer [this message]
2016-11-17 14:17 ` Eric Dumazet
2016-11-17 14:57 ` Jesper Dangaard Brouer
2016-11-17 16:21 ` Eric Dumazet
2016-11-17 18:30 ` Jesper Dangaard Brouer
2016-11-17 18:51 ` Eric Dumazet
2016-11-17 21:19 ` Jesper Dangaard Brouer
2016-11-17 21:44 ` Eric Dumazet
2016-11-17 23:08 ` Rick Jones
2016-11-18 0:37 ` Julian Anastasov
2016-11-18 0:42 ` Rick Jones
2016-11-18 17:12 ` Jesper Dangaard Brouer
2016-11-21 16:03 ` Jesper Dangaard Brouer
2016-11-21 18:10 ` Eric Dumazet
2016-11-29 6:58 ` [WIP] net+mlx4: auto doorbell Eric Dumazet
2016-11-30 11:38 ` Jesper Dangaard Brouer
2016-11-30 15:56 ` Eric Dumazet
2016-11-30 19:17 ` Jesper Dangaard Brouer
2016-11-30 19:30 ` Eric Dumazet
2016-11-30 22:30 ` Jesper Dangaard Brouer
2016-11-30 22:40 ` Eric Dumazet
2016-12-01 0:27 ` Eric Dumazet
2016-12-01 1:16 ` Tom Herbert
2016-12-01 2:32 ` Eric Dumazet
2016-12-01 2:50 ` Eric Dumazet
2016-12-02 18:16 ` Eric Dumazet
2016-12-01 5:03 ` Tom Herbert
2016-12-01 19:24 ` Willem de Bruijn
2016-11-30 13:50 ` Saeed Mahameed
2016-11-30 15:44 ` Eric Dumazet
2016-11-30 16:27 ` Saeed Mahameed
2016-11-30 17:28 ` Eric Dumazet
2016-12-01 12:05 ` Jesper Dangaard Brouer
2016-12-01 14:24 ` Eric Dumazet
2016-12-01 16:04 ` Jesper Dangaard Brouer
2016-12-01 17:04 ` Eric Dumazet
2016-12-01 19:17 ` Jesper Dangaard Brouer
2016-12-01 20:11 ` Eric Dumazet
2016-12-01 20:20 ` David Miller
2016-12-01 22:10 ` Eric Dumazet
2016-12-02 14:23 ` Eric Dumazet
2016-12-01 21:32 ` Alexander Duyck
2016-12-01 22:04 ` Eric Dumazet
2016-11-17 17:34 ` Netperf UDP issue with connected sockets David Laight
2016-11-17 22:39 ` Alexander Duyck
2016-11-17 17:42 ` Rick Jones
2016-11-28 18:33 ` Rick Jones
2016-11-28 18:40 ` Rick Jones
2016-11-30 10:43 ` Jesper Dangaard Brouer
2016-11-30 17:42 ` Rick Jones
2016-11-30 18:11 ` David Miller
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