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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 01 Oct 2014 16:05:31 -0400
From:	Jamal Hadi Salim <jhs@...atatu.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
CC:	Tom Herbert <therbert@...gle.com>,
	David Miller <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Florian Westphal <fw@...len.de>,
	Daniel Borkmann <dborkman@...hat.com>,
	Alexander Duyck <alexander.duyck@...il.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Dave Taht <dave.taht@...il.com>,
	Toke Høiland-Jørgensen <toke@...e.dk>
Subject: Re: [net-next PATCH V5] qdisc: bulk dequeue support for qdiscs with
 TCQ_F_ONETXQUEUE

On 10/01/14 15:47, Jesper Dangaard Brouer wrote:

>
> Answer is yes.  It is very easy with simple netperf TCP_STREAM to cause
> queueing >1 packet in the qdisc layer.

If that is the case, I withdraw any doubts i had.
Can you please specify this in your commit logs for patch 0?

> If tuned (according to my blog,
> unloading netfilter etc.) then a single netperf TCP_STREAM will max out
> 10Gbit/s and cause a standing queue.
>

You should describe such tuning in the patch log (hard to read
blogs for more than 30 seconds; write a paper if you want to provide
more details).

> I'm monitoring backlog of qdiscs, and I always see >1 backlog, I never
> saw a standing queue of 1 packet in my testing.  Either the backlog
> area is high 100-200 packets, or 0 backlog.  (With fake pktgen/trafgen
> style tests, it's possible to cause 1000 backlog).

It would be nice to actually collect such stats. Monitoring the backlog
via dumping qdisc stats is a good start - but actually keeping traces
of average bulk size is more useful.

cheers,
jamal
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html