[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 15:15:53 UTC 2019
On 04.07.2019 18:13, Ian Stokes 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?
custom_stats->counters[0].value = dev->tx_retries;
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