Subject: Re: [net-next PATCH V5] qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE

From: Jamal Hadi Salim <[email-masked]>
Date: Wed, 01 Oct 2014 09:17:39 -0400

On 09/30/14 14:20, David Miller wrote:
> From: Jamal Hadi Salim <[email-masked]>
> Date: Tue, 30 Sep 2014 07:07:37 -0400
>
>> Note, there are benefits as you have shown - but i would not
>> consider those to be standard use cases (actully one which would
>> have shown clear win is the VM thing Rusty was after).
>
> I completely disagree, you will see at least decreased cpu utilization
> for a very common case, bulk single stream transfers.
>

So lets say the common use case is:
= modern day cpu (pick some random cpu)
= 1-10 Gbps ethernet (not 100mbps)
= 1-24 tcp or udp bulk (you said one, Jesper had 24 which sounds better)

Run with test cases:
a) unchanged (no bulking code added at all)
vs
b) bulking code added and used
vs
c) bulking code added and *not* used

Jesper's results are comparing #b and #c.

And if #b + #c are slightly worse or equal then we have a win;->

Again, I do believe things like traffic generators or the VM io
or something like tuntap that crosses user space will have a clear
benefit (but are those common use cases?).

cheers,
jamal