[ovs-dev] [PATCH v4 2/3] netdev-dpdk: Add custom stat for vhost tx retries.

David Marchand david.marchand at redhat.com
Thu Jul 4 15:15:41 UTC 2019


On Thu, Jul 4, 2019 at 5:13 PM Ian Stokes <ian.stokes at intel.com> wrote:

> On 7/4/2019 12:18 PM, Ilya Maximets wrote:
> > On 04.07.2019 14:06, David Marchand wrote:
> >>
> >>
> >> On Thu, Jul 4, 2019 at 12:42 PM Ilya Maximets <i.maximets at samsung.com
> <mailto:i.maximets at samsung.com>> wrote:
> >>
> >>      On 03.07.2019 18:03, Ian Stokes wrote:
> >>      > On 7/2/2019 1:32 AM, Kevin Traynor wrote:
> >>      >> vhost tx retries may occur, and it can be a sign that
> >>      >> the guest is not optimally configured.
> >>      >>
> >>      >> Add a custom stat so a user will know if vhost tx retries are
> >>      >> occurring and hence give a hint that guest config should be
> >>      >> examined.
> >>      >>
> >>      >
> >>      > Thanks Kevin, tests ok for me.
> >>      >
> >>      > Just a general comment on the design. In comparison to the
> previous approach proposed there seems to be more required with the custom
> stat approach below.
> >>      >
> >>      > This may be ok as the retry is very OVS DPDK specific and
> doesn;t come dor lets say DPDK (unlike the XTATS).
> >>      >
> >>      > @Ilya, whats your thoughts? Is this approach preferable for you
> rather than adding it to the general stats for all devices? (in which case
> I agree, they will not be used for dpdk types so will not be of use).
> >>
> >>      I think, It's better to keep this in custom stats section since
> >>      no other port types are going to use it in a near future.
> >>
> >>      Have a few style/naming comments inline.
> >>
> >>      >
> >>      > One other minor comment below.
> >>      >
> >>      >> Signed-off-by: Kevin Traynor <ktraynor at redhat.com <mailto:
> ktraynor at redhat.com>>
> >>      >> ---
> >>      >>   Documentation/topics/dpdk/vhost-user.rst |  5 ++++
> >>      >>   lib/netdev-dpdk.c                        | 38
> +++++++++++++++++++++++-
> >>      >>   2 files changed, 42 insertions(+), 1 deletion(-)
> >>      >>
> >>      >> diff --git a/Documentation/topics/dpdk/vhost-user.rst
> b/Documentation/topics/dpdk/vhost-user.rst
> >>      >> index 5f393aced..368f44520 100644
> >>      >> --- a/Documentation/topics/dpdk/vhost-user.rst
> >>      >> +++ b/Documentation/topics/dpdk/vhost-user.rst
> >>      >> @@ -521,4 +521,9 @@ The guest should also have sufficient cores
> dedicated for consuming and
> >>      >>   processing packets at the required rate.
> >>      >>   +The amount of Tx retries on a vhost-user or
> vhost-user-client interface can be
> >>      >> +shown with::
> >>      >> +
> >>      >> +  $ ovs-vsctl get Interface dpdkvhostclient0
> statistics:tx_retries
> >>      >> +
> >>      >>   vhost-user Dequeue Zero Copy (experimental)
> >>      >>   -------------------------------------------
> >>      >> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> >>      >> index a380b6ffe..d3e02d389 100644
> >>      >> --- a/lib/netdev-dpdk.c
> >>      >> +++ b/lib/netdev-dpdk.c
> >>      >> @@ -139,4 +139,10 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF /
> ROUND_DOWN_POW2(MAX_NB_MBUF / MIN_NB_MBUF))
> >>      >>   #define XSTAT_RX_JABBER_ERRORS           "rx_jabber_errors"
> >>      >>   +/* Size of vHost custom stats. */
> >>      >> +#define VHOST_STAT_TX_RETRIES_SIZE    1
> >>
> >>      I think, it's better to rename to something like
> VHOST_CUSTOM_STATS_SIZE.
> >>
> >>
> >> +1
> >>
> >>
> >>
> >>      >> +
> >>      >> +/* Name of vHost custom stats. */
> >>
> >>      s/Name/Names/ ?
> >>
> >>      >> +#define VHOST_STAT_TX_RETRIES    "tx_retries" > +
> >>      >
> >>      > The alignment of the defines above look odd as they are not
> aligned with the existing DPDK XSTAT name definitions. It's only minor, as
> Kevin is on leave I think this will be ok to change on commit if there are
> no objections.
> >>
> >>      Sure.
> >>
> >>      >
> >>      > Regards
> >>      > Ian
> >>      >>   #define SOCKET0              0
> >>      >>   @@ -434,7 +440,9 @@ struct netdev_dpdk {
> >>      >>       PADDED_MEMBERS(CACHE_LINE_SIZE,
> >>      >>           struct netdev_stats stats;
> >>      >> +        /* Custom stat for retries when unable to transmit. */
> >>      >> +        uint64_t tx_retries;
> >>      >>           /* Protects stats */
> >>      >>           rte_spinlock_t stats_lock;
> >>      >> -        /* 44 pad bytes here. */
> >>      >> +        /* 4 pad bytes here. */
> >>      >>       );
> >>      >>   @@ -1190,4 +1198,6 @@ common_construct(struct netdev *netdev,
> dpdk_port_t port_no,
> >>      >>       dev->rte_xstats_ids_size = 0;
> >>      >>   +    dev->tx_retries = 0;
> >>      >> +
> >>      >>       return 0;
> >>      >>   }
> >>      >> @@ -2381,4 +2391,5 @@ __netdev_dpdk_vhost_send(struct netdev
> *netdev, int qid,
> >>      >>       netdev_dpdk_vhost_update_tx_counters(&dev->stats, pkts,
> total_pkts,
> >>      >>                                            cnt + dropped);
> >>      >> +    dev->tx_retries += MIN(retries, VHOST_ENQ_RETRY_NUM);
> >>      >>       rte_spinlock_unlock(&dev->stats_lock);
> >>      >>   @@ -2818,4 +2829,27 @@ netdev_dpdk_get_custom_stats(const
> struct netdev *netdev,
> >>      >>   }
> >>      >>   +static int
> >>      >> +netdev_dpdk_vhost_get_custom_stats(const struct netdev *netdev,
> >>      >> +                                   struct netdev_custom_stats
> *custom_stats)
> >>      >> +{
> >>      >> +    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> >>      >> +
> >>      >> +    ovs_mutex_lock(&dev->mutex);
> >>      >> +
> >>      >> +    custom_stats->size = VHOST_STAT_TX_RETRIES_SIZE;
> >>      >> +    custom_stats->counters = (struct netdev_custom_counter *)
> >>      >> +                                 xzalloc(sizeof(struct
> netdev_custom_counter));
> >>
> >>      Since we have a _SIZE, we, probably, need to use it while
> allocation.
> >>      With this and a few coding-style fixes, this line should look like:
> >>
> >>          custom_stats->counters = xcalloc(VHOST_STAT_TX_RETRIES_SIZE,
> >>                                           sizeof
> *custom_stats->counters);
> >>
> >>
> >> Can I suggest?
> >>      custom_stats->counters = xcalloc(custom_stats->size,
> >>                                       sizeof *custom_stats->counters);
> >
> > Sure. This looks fine for me too.
> >
> >>
> >>      >> +    ovs_strlcpy(custom_stats->counters->name,
> VHOST_STAT_TX_RETRIES,
> >>      >> +                NETDEV_CUSTOM_STATS_NAME_SIZE);
> >>      >> +
> >>      >> +    rte_spinlock_lock(&dev->stats_lock);
> >>      >> +    custom_stats->counters->value = dev->tx_retries;
> >>
> >>
> >>
> >> I have a patch after this that will add another stats, so I'd rather
> see custom_stats->counters[0]. than custom_stats->counters->
> >
> > +1.
> > This is also in line with my previous comment about having a _SIZE.
>
> Just to clarify above, maybe I misunderstood what you meant, but are you
> suggesting
>
> custom_stats->counters[0] = dev->tx_retries;
>
> I don't think that will work as it will be an incorrect type assignment
> right?
>
>
I meant:
    ovs_strlcpy(custom_stats->counters[0].name, VHOST_STAT_TX_RETRIES,
                NETDEV_CUSTOM_STATS_NAME_SIZE);

    custom_stats->counters[0].value = dev->tx_retries;


-- 
David Marchand


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