From: Jamal Hadi Salim <jhs@mojatatu•com>
To: John Fastabend <john.fastabend@gmail•com>,
Cong Wang <xiyou.wangcong@gmail•com>
Cc: John Fastabend <john.r.fastabend@intel•com>,
Eric Dumazet <eric.dumazet@gmail•com>,
Linux Kernel Network Developers <netdev@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>
Subject: Re: [RFC Patch net-next] net_sched: make classifying lockless on ingress
Date: Thu, 26 Dec 2013 07:02:01 -0500 [thread overview]
Message-ID: <52BC1AB9.8010407@mojatatu.com> (raw)
In-Reply-To: <52B924F1.9020201@gmail.com>
On 12/24/13 01:08, John Fastabend wrote:
>
> In this case I was specifically talking about statistics so the
> bstats and qstats.
>
Thats my thinking as well. Mostly control plane requests would
drive it. Assuming it is real world and not a benchmark test - then
you can afford to be loosely synchronized.
> As long as the qdisc's do not require global state this works well
> enough. However as Jamal keeps pointing out the problem is any qdisc
> which requires global state requires locking (I paraphrase but I think
> replicate the spirit correctly) and this doesn't work well with many
> CPUs. So you either replicate the qdiscs one per queue like we do in
> the mq and mqprio case effectively removing any global state or you
> develop qdiscs that don't require global state or at least work with
> eventually consistent data to avoid the constant syncing of data.
>
> I think though a qdisc per nic queue is really not as bad as you think.
> For example we do this on the tx side and it works OK. Note its per
> RX queue and not per CPU.
>
And it is as you said earlier a configuration issue.
cheers,
jamal
next prev parent reply other threads:[~2013-12-26 12:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-20 23:28 [RFC Patch net-next] net_sched: make classifying lockless on ingress Cong Wang
2013-12-20 23:49 ` Eric Dumazet
2013-12-20 23:57 ` Cong Wang
2013-12-21 0:08 ` Eric Dumazet
2013-12-21 0:24 ` Cong Wang
2013-12-21 2:32 ` John Fastabend
2013-12-21 22:11 ` Jamal Hadi Salim
2013-12-21 23:09 ` John Fastabend
2013-12-22 16:01 ` Jamal Hadi Salim
2013-12-24 0:56 ` Cong Wang
2013-12-24 6:08 ` John Fastabend
2013-12-26 12:02 ` Jamal Hadi Salim [this message]
2013-12-21 1:09 ` John Fastabend
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