From: Hannes Frederic Sowa <hannes@stressinduktion.org>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, therbert@google.com, jhs@mojatatu.com,
edumazet@google.com, jeffrey.t.kirsher@intel.com,
rusty@rustcorp.com.au, dborkman@redhat.com, brouer@redhat.com,
john.r.fastabend@intel.com
Subject: Re: [PATCH 0/2] Get rid of ndo_xmit_flush
Date: Tue, 02 Sep 2014 00:31:09 +0200 [thread overview]
Message-ID: <1409610669.21965.55.camel@localhost> (raw)
In-Reply-To: <20140901.145646.174847768842584425.davem@davemloft.net>
On Mo, 2014-09-01 at 14:56 -0700, David Miller wrote:
> From: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Date: Mon, 01 Sep 2014 22:05:42 +0200
>
> > But as soon as we try to make Qdiscs absolutely lockless, we don't have
> > any guard that we don't concurrently dequeue skbs from it and suddenly
> > one Qdisc dequeue processing entity couldn't notify the driver that the
> > end of the batching was reached. I think this could become a problem
> > depending on how much of the locking is removed?
>
> I am certain that batching will require taking the device transmit
> lock over the ->ndo_start_xmit() invocations, and therefore the
> deferral decisions must atomically be made inside of that context.
I'll stop to throw doubt into this discussion now. ;)
I am afraid that TX-lock is per nic-queue and it won't work out that
easy because skbs for different queues can reside in a Qdisc.
Bye,
Hannes
next prev parent reply other threads:[~2014-09-01 22:31 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 23:34 [PATCH 0/2] Get rid of ndo_xmit_flush David Miller
2014-08-26 6:28 ` Jesper Dangaard Brouer
2014-08-26 10:13 ` Jesper Dangaard Brouer
2014-08-26 12:52 ` Jesper Dangaard Brouer
2014-08-26 16:43 ` Alexander Duyck
2014-08-27 7:48 ` Jesper Dangaard Brouer
2014-08-27 8:37 ` Jesper Dangaard Brouer
2014-08-26 14:40 ` Jamal Hadi Salim
2014-09-01 0:37 ` Rusty Russell
2014-08-27 12:19 ` Jesper Dangaard Brouer
2014-08-27 20:43 ` David Miller
2014-08-27 12:31 ` Hannes Frederic Sowa
2014-08-27 13:23 ` Eric Dumazet
2014-08-27 13:56 ` Jesper Dangaard Brouer
2014-08-27 14:09 ` Eric Dumazet
2014-08-27 20:48 ` David Miller
2014-08-27 20:46 ` David Miller
2014-08-27 20:45 ` David Miller
2014-08-28 1:42 ` Hannes Frederic Sowa
2014-08-30 3:22 ` David Miller
2014-08-30 10:23 ` Jesper Dangaard Brouer
2014-09-01 20:05 ` Hannes Frederic Sowa
2014-09-01 21:56 ` David Miller
2014-09-01 22:31 ` Hannes Frederic Sowa [this message]
2014-09-01 22:35 ` David Miller
2014-08-27 18:28 ` Cong Wang
2014-08-27 19:31 ` Tom Herbert
2014-08-27 20:53 ` David Miller
2014-08-27 20:51 ` David Miller
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