[dpdk-dev] [PATCH v2] net/vhost: add pmd xstats
Yang, Zhiyong
zhiyong.yang at intel.com
Mon Sep 19 04:48:31 CEST 2016
Hi, Yuanhan:
Thanks a lot for your comments and suggestion in so detail. I will send v3 patch
as soon as possible.
--Zhiyong
> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Sunday, September 18, 2016 9:17 PM
> To: Yang, Zhiyong <zhiyong.yang at intel.com>
> Cc: dev at dpdk.org; thomas.monjalon at 6wind.com; pmatilai at redhat.com
> Subject: Re: [PATCH v2] net/vhost: add pmd xstats
>
> On Wed, Sep 14, 2016 at 07:43:36AM +0000, Yang, Zhiyong wrote:
> > Hi, yuanhan:
> > Thanks so much for your detailed comments.
> >
> > > -----Original Message-----
> > > From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> > > Sent: Wednesday, September 14, 2016 2:20 PM
> > > To: Yang, Zhiyong <zhiyong.yang at intel.com>
> > > Cc: dev at dpdk.org; thomas.monjalon at 6wind.com; pmatilai at redhat.com
> > > Subject: Re: [PATCH v2] net/vhost: add pmd xstats
> > >
> > > On Fri, Sep 09, 2016 at 04:15:27PM +0800, Zhiyong Yang wrote:
> > > > +struct vhost_xstats {
> > > > + uint64_t stat[16];
> > > > +};
> > > > +
> > > > struct vhost_queue {
> > > > int vid;
> > > > rte_atomic32_t allow_queuing;
> > > > @@ -85,7 +89,8 @@ struct vhost_queue {
> > > > uint64_t missed_pkts;
> > > > uint64_t rx_bytes;
> > > > uint64_t tx_bytes;
> > >
> > > I'd suggest to put those statistic counters to vhost_stats struct,
> > > which could simplify the xstats_reset code a bit.
> > >
> >
> > I consider this point when I define it, but those statistic counters
> > are used by pmd stats, not only by pmd xstats, I'm not clear if I
> > can modify those code. If permitted, I will do it as you said.
>
> For sure you can modify the code :) I just would suggest to do in an single
> patch, as stated before (and below).
>
Ok. I will do that.
> > > > + char name[RTE_ETH_VHOST_XSTATS_NAME_SIZE];
> > > > + uint64_t offset;
> > > > +};
> > > > +
> > > > +/* [rt]_qX_ is prepended to the name string here */ static void
> > > > +vhost_dev_xstats_reset(struct rte_eth_dev *dev) {
> > > > + struct vhost_queue *vqrx = NULL;
> > > > + struct vhost_queue *vqtx = NULL;
> > > > + unsigned int i = 0;
> > > > +
> > > > + for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > > > + if (!dev->data->rx_queues[i])
> > > > + continue;
> > > > + vqrx = (struct vhost_queue *)dev->data->rx_queues[i];
> > >
> > > Unnecessary cast.
> > >
> > The definition of rx_queues is void **rx_queues;
>
> Yes, but rx_queues[i] is with type "void *", so the cast is not necessary.
>
I'm confused if void * ptr can access a member of struct directly. Or Need
I explicitly cast it when using it?
> > > > + }
> > > > + }
> > > > + /* non-multi/broadcast, multi/broadcast, including those
> > > > + * that were discarded or not sent.
> > >
> > > Hmmm, I don't follow it. You may want to reword it.
> > >
> > > > from rfc2863
> > >
> > > Which section and which page?
> > >
> > The packets received are not considered "discarded", because receiving
> > packets via Memory, not by physical NIC. Mainly for the number of
> > transmit the packets
>
> It still took me some time to understand you.
>
> > RFC2863 page 35 ifOutUcastPkts(non-multi/broadcast)
>
> So, by your term, unicast == non-multicast/broadcast? If so, I'd suggest to
> use term "unicast" but not something else: it just introduces confusions.
>
You are right . non-multicast/broadcast is equal to unicast. I agree with you
And will modify it as you say.
> And in this case, I guess you were trying to say:
>
> /*
> * According to RFC 2863 section ifHCOutMulticastPkts, ... and ...,
> * the counter "unicast", "multicast" and "broadcast" are also
> * increased when packets are not transmitted successfully.
> */
>
Yes.
> Well, you might still need reword it.
>
> After taking a bit closer look at the code, I'd suggest to do the countings like
> following:
>
> - introduce a help function to increase the "broadcast" or "multicast"
> counter, say "count_multicast_broadcast(struct vhost_stats *stats, mbuf)".
>
> - introduce a generic function to update the generic counters: this
> function just counts those packets have been successfully transmitted
> or received.
>
> It also invoke above helper function for multicast counting.
>
> It basically looks like the function vhost_update_packet_xstats,
> execpt that it doesn't handle those failure packets: it will be
> handled in following part.
>
> - since the case "couting multicast and broadcast with failure packts"
> only happens in the Tx side, we could do those countings only in
> eth_vhost_tx():
>
> nb_tx = rte_vhost_enqueue_burst(r->vid,
> r->virtqueue_id, bufs, nb_bufs);
>
> missed = nb_bufs - nb_tx;
> /* put above comment here */
> if (missed) {
> for_each_mbuf(mbuf) {
> count_multicast_broadcast(&vq->stats, mbuf);
> }
> }
>
> - there is no need to update "stat[10]" (unicast), since it can be calculated
> from other counters, meaning we could just get the right value on query.
>
> This could save some cycles.
>
Ok, Your comments are detailed and clear. I will consider to remove unicast
and modify update functions.
> Feel free to phone me if you have any doubts.
>
> --yliu
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