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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: Or Gerlitz <gerlitz.or@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	John Fastabend <john.r.fastabend@intel.com>,
	Linux Netdev List <netdev@vger.kernel.org>,
	Amir Vadai <amirv@mellanox.com>,
	Or Gerlitz <or.gerlitz@gmail.com>
Subject: Re: [PATCH net-next] mlx4: optimize xmit path
Date: Sun, 28 Sep 2014 19:22:11 -0700	[thread overview]
Message-ID: <1411957331.15768.91.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <CAMEtUuw861ZM+jvtFnJtwTS9krUFy09Z+rj-9LJ3UYRzOEd9zA@mail.gmail.com>

On Sun, 2014-09-28 at 13:49 -0700, Alexei Starovoitov wrote:

> I see. So xmit_more=true overrides blueflame=on settings.

Yes, unless Mellanox folks have another way.

> I wonder what is the performance difference bf=on vs bf=off,
> also whether a burst of N packets via bf is slower than
> burst via queue+doorbell.
> Some fun exploration for driver experts :)

Prior situation : bf=on : ~4.5 Mpps

queue + doorbell every 8 packets : ~8 Mpps, up to 10Mpps if tuned
properly.

Rewritten mlx4 tx path and no burst (bf=on doorbell at every packet) :
5.3 Mpps

With the full mlx4 patch and burst = 8 -> 14.9 Mpps

This is on a 40Gb NIC, with 108 bytes packets.

(Using <= 104 bytes packets actually gives lower pps because of
'inlining' done by the driver :  8 Mpps for PKTSIZE=40 )

# cat /sys/module/mlx4_en/parameters/inline_thold
104

  reply	other threads:[~2014-09-29  2:22 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-28 18:07 [PATCH net-next] mlx4: optimize xmit path Alexei Starovoitov
2014-09-28 18:52 ` Eric Dumazet
2014-09-28 20:49   ` Alexei Starovoitov
2014-09-29  2:22     ` Eric Dumazet [this message]
2014-09-29  5:08       ` Alexei Starovoitov
  -- strict thread matches above, loose matches on Subject: below --
2014-09-26  0:46 [RFC PATCH net-next] net: pktgen: packet bursting via skb->xmit_more Alexei Starovoitov
2014-09-26  1:20 ` Eric Dumazet
2014-09-26  7:42   ` Eric Dumazet
2014-09-27 20:43     ` Eric Dumazet
2014-09-27 20:55       ` Or Gerlitz
2014-09-27 21:30         ` Eric Dumazet
2014-09-27 22:56           ` [PATCH net-next] mlx4: optimize xmit path Eric Dumazet
2014-09-27 23:44             ` Hannes Frederic Sowa
2014-09-28  0:05               ` Eric Dumazet
2014-09-28  0:22                 ` Hannes Frederic Sowa
2014-09-28 12:42             ` Eric Dumazet
2014-09-28 14:35             ` Or Gerlitz
2014-09-28 16:03               ` Eric Dumazet

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