[ovs-dev] [RFC PATCH] netdev-dpdk: Expose per rxq/txq basic statistics.

Maxime Coquelin maxime.coquelin at redhat.com
Fri Nov 19 12:45:53 UTC 2021



On 11/19/21 13:08, Kevin Traynor wrote:
> On 19/11/2021 10:31, David Marchand wrote:
>> On Fri, Nov 19, 2021 at 10:40 AM Maxime Coquelin
>> <maxime.coquelin at redhat.com> wrote:
>>>
>>> Hi Kevin, David,
>>>
>>> On 11/18/21 16:31, Kevin Traynor wrote:
>>>> On 15/10/2021 16:04, David Marchand wrote:
>>>>> When troubleshooting multiqueue setups, having per queue statistics 
>>>>> helps
>>>>> checking packets repartition in rx and tx queues.
>>>>>
>>>>> Per queue statistics are exported by most DPDK drivers (with 
>>>>> capability
>>>>> RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS). But since OVS only filters 
>>>>> statistics
>>>>> it exposes, there is nothing to request in DPDK API.
>>>>>
>>>>> Extend existing filter with a regular expression.
>>>>> string_ends_with() helper is not used anymore, and removed as a
>>>>> consequence.
>>>>>
>>>>> Querying statistics with
>>>>> $ ovs-vsctl get interface dpdk0 statistics | \
>>>>>     sed -e 's#[{}]##g' -e 's#, #\n#g'
>>>>>
>>>>> and comparing gives:
>>>>> @@ -13,7 +13,12 @@
>>>>>    rx_phy_crc_errors=0
>>>>>    rx_phy_in_range_len_errors=0
>>>>>    rx_phy_symbol_errors=0
>>>>> +rx_q0_bytes=0
>>>>>    rx_q0_errors=0
>>>>> +rx_q0_packets=0
>>>>> +rx_q1_bytes=0
>>>>> +rx_q1_errors=0
>>>>> +rx_q1_packets=0
>>>>>    rx_wqe_errors=0
>>>>>    tx_broadcast_packets=0
>>>>>    tx_bytes=0
>>>>> @@ -27,3 +32,13 @@
>>>>>    tx_pp_rearm_queue_errors=0
>>>>>    tx_pp_timestamp_future_errors=0
>>>>>    tx_pp_timestamp_past_errors=0
>>>>> +tx_q0_bytes=0
>>>>> +tx_q0_packets=0
>>>>> +tx_q1_bytes=0
>>>>> +tx_q1_packets=0
>>>>> +tx_q2_bytes=0
>>>>> +tx_q2_packets=0
>>>>> +tx_q3_bytes=0
>>>>> +tx_q3_packets=0
>>>>> +tx_q4_bytes=0
>>>>> +tx_q4_packets=0
>>>>>
>>>>> Signed-off-by: David Marchand <david.marchand at redhat.com>
>>>>
>>>> The patch looks good but I tested with with ixgbe, and seeing something
>>>> I am unsure of. I changed the number of rxqs to 11 but I am only seeing
>>>> stats for q0. i'm not sure if this because there was no traffic yet
>>>> (even though there is also no traffic on q0). i will set up a traffic
>>>> gen and see what happens when the q1-q10 receives traffic.
>>>
>>> I think the problem is that when port reconfiguration is called because
>>> the number of queues changed, netdev_dpdk_clear_xstats() is not called.
>>>
>>> So the next time netdev_dpdk_configure_xstats() is called, it returns
>>> true early as it is already configured. So old configuration is keeped.
>>>
>>> When increasing the number of queues, I think we get your behavior, i.e.
>>> only previous number of queues counters are disaplayed. But when
>>> decreasing the number of queues, I think rte_eth_xstats_get_by_id() will
>>> fail.
>>>
>>> I think calling netdev_dpdk_clear_xstats() in netdev_dpdk_reconfigure()
>>> should fix your issue.
>>
>> Thanks for the analysis.
>>
>> I'll need a bit more time to dig in (I don't understand the logic
>> behind the configure_xstats/clear_xstats stuff).
>> In any case, it seems this is a bug predating my patch.
>>
>>
> 
> Thanks Maxime. Yes, that seems to be explanation for it.
> 
> The issue was also present with the txqs when the number of PMDs was 
> increased/decreased, hence changing requested txqs. I added below and it 
> is showing the right amount of rx/tx queues now.
> 
> I'm not sure it's an existing bug that we'd backport a fix for as the 
> num queues changing wouldn't have previously impacted because of the 
> filter. It seems more like a short cut that we now can't keep :-)

As per David's commit log above, don't we need to backport it because we 
already dumped rxqN_error counter before?

> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index ca92c947a..720041c34 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -1876,4 +1876,5 @@ dpdk_set_rxq_config(struct netdev_dpdk *dev, const 
> struct smap *args)
>           dev->requested_n_rxq = new_n_rxq;
>           netdev_request_reconfigure(&dev->up);
> +        netdev_dpdk_clear_xstats(dev);
>       }
>   }
> @@ -2109,4 +2110,5 @@ netdev_dpdk_set_tx_multiq(struct netdev *netdev, 
> unsigned int n_txq)
>       dev->requested_n_txq = n_txq;
>       netdev_request_reconfigure(netdev);
> +    netdev_dpdk_clear_xstats(dev);
> 



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