From: Jesper Dangaard Brouer <brouer@redhat.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: fw@strlen.de, jhs@mojatatu.com, alexei.starovoitov@gmail.com,
eric.dumazet@gmail.com, netdev@vger.kernel.org,
brouer@redhat.com, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [RFC PATCH v2 08/10] net: sched: pfifo_fast use alf_queue
Date: Fri, 15 Jul 2016 12:09:36 +0200 [thread overview]
Message-ID: <20160715120936.0b339b2a@redhat.com> (raw)
In-Reply-To: <578829C7.8060604@gmail.com>
On Thu, 14 Jul 2016 17:09:43 -0700
John Fastabend <john.fastabend@gmail.com> wrote:
> >> static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
> >> struct sk_buff **to_free)
> >> {
> >> - if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
> >> - int band = prio2band[skb->priority & TC_PRIO_MAX];
> >> - struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
> >> - struct sk_buff_head *list = band2list(priv, band);
> >> -
> >> - priv->bitmap |= (1 << band);
> >> - qdisc->q.qlen++;
> >> - return __qdisc_enqueue_tail(skb, qdisc, list);
> >> - }
> >> + int band = prio2band[skb->priority & TC_PRIO_MAX];
> >> + struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
> >> + struct skb_array *q = band2list(priv, band);
> >> + int err;
> >>
> >> - return qdisc_drop(skb, qdisc, to_free);
> >> + err = skb_array_produce_bh(q, skb);
> >
> > Do you need the _bh variant here? (Doesn't the qdisc run with BH disabled?)
> >
> >
>
> Yep its inside rcu_read_lock_bh().
The call rcu_read_lock_bh() already disabled BH (local_bh_disable()).
Thus, you can use the normal variants of skb_array_produce(), it is
(approx 20 cycles) faster than the _bh variant...
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2016-07-15 10:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 6:19 [RFC PATCH v2 00/10] running qdiscs without qdisc_lock John Fastabend
2016-07-14 6:19 ` [RFC PATCH v2 01/10] net: sched: allow qdiscs to handle locking John Fastabend
2016-07-14 6:44 ` John Fastabend
2016-07-14 6:20 ` [RFC PATCH v2 02/10] net: sched: qdisc_qlen for per cpu logic John Fastabend
2016-07-14 6:20 ` [RFC PATCH v2 03/10] net: sched: provide per cpu qstat helpers John Fastabend
2016-07-14 6:21 ` [RFC PATCH v2 04/10] net: sched: a dflt qdisc may be used with per cpu stats John Fastabend
2016-07-14 6:21 ` [RFC PATCH v2 05/10] net: sched: per cpu gso handlers John Fastabend
2016-07-14 6:22 ` [RFC PATCH v2 06/10] net: sched: support qdisc_reset on NOLOCK qdisc John Fastabend
2016-07-14 6:22 ` [RFC PATCH v2 07/10] net: sched: support skb_bad_tx with lockless qdisc John Fastabend
2016-07-14 6:23 ` [RFC PATCH v2 08/10] net: sched: pfifo_fast use alf_queue John Fastabend
2016-07-14 15:11 ` Jesper Dangaard Brouer
2016-07-15 0:09 ` John Fastabend
2016-07-15 10:09 ` Jesper Dangaard Brouer [this message]
2016-07-15 17:29 ` John Fastabend
2016-07-14 23:42 ` Alexei Starovoitov
2016-07-15 0:07 ` John Fastabend
2016-07-15 11:23 ` Jesper Dangaard Brouer
2016-07-15 22:18 ` John Fastabend
2016-07-15 22:48 ` Alexei Starovoitov
2016-07-14 6:23 ` [RFC PATCH v2 09/10] net: sched: helper to sum qlen John Fastabend
2016-07-14 6:24 ` [RFC PATCH v2 10/10] net: sched: add support for TCQ_F_NOLOCK subqueues to sch_mq John Fastabend
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