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

Ilya Maximets i.maximets at samsung.com
Thu Jul 4 11:18:24 UTC 2019


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.

> 
>  
> 
>     >> +    rte_spinlock_unlock(&dev->stats_lock);
>     >> +
>     >> +    ovs_mutex_unlock(&dev->mutex);
>     >> +
>     >> +    return 0;
>     >> +}
>     >> +
>     >>   static int
>     >>   netdev_dpdk_get_features(const struct netdev *netdev,
>     >> @@ -4398,4 +4432,5 @@ static const struct netdev_class dpdk_vhost_class = {
>     >>       .get_carrier = netdev_dpdk_vhost_get_carrier,
>     >>       .get_stats = netdev_dpdk_vhost_get_stats,
>     >> +    .get_custom_stats = netdev_dpdk_vhost_get_custom_stats,
>     >>       .get_status = netdev_dpdk_vhost_user_get_status,
>     >>       .reconfigure = netdev_dpdk_vhost_reconfigure,
>     >> @@ -4413,4 +4448,5 @@ static const struct netdev_class dpdk_vhost_client_class = {
>     >>       .get_carrier = netdev_dpdk_vhost_get_carrier,
>     >>       .get_stats = netdev_dpdk_vhost_get_stats,
>     >> +    .get_custom_stats = netdev_dpdk_vhost_get_custom_stats,
>     >>       .get_status = netdev_dpdk_vhost_user_get_status,
>     >>       .reconfigure = netdev_dpdk_vhost_client_reconfigure,
>     >>
> 
> 
> 
> 
> -- 
> David Marchand


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