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From: Ferruh Yigit <ferruh.yigit@intel.com>
To: "Min Hu (Connor)" <humin29@huawei.com>,
	Thomas Monjalon <thomas@monjalon.net>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
Cc: Olivier Matz <olivier.matz@6wind.com>,
	Stephen Hemminger <stephen@networkplumber.org>,
	"techboard@dpdk.org" <techboard@dpdk.org>,
	bruce.richardson@intel.com,
	"jerinj@marvell.com" <jerinj@marvell.com>,
	Ray Kinsella <mdr@ashroe.eu>,
	dev@dpdk.org
Subject: Re: [dpdk-dev] [dpdk-techboard] [PATCH V5 1/2] dpdk: resolve compiling errors for per-queue stats
Date: Fri, 9 Oct 2020 21:32:10 +0100	[thread overview]
Message-ID: <c991827e-9415-855c-9d71-30d52dc804d5@intel.com> (raw)
In-Reply-To: <20201006083325.GF21395@platinum>

On 10/6/2020 9:33 AM, Olivier Matz wrote:
> Hi,
> 
> On Mon, Oct 05, 2020 at 01:23:08PM +0100, Ferruh Yigit wrote:
>> On 9/28/2020 4:43 PM, Stephen Hemminger wrote:
>>> On Mon, 28 Sep 2020 17:24:26 +0200
>>> Thomas Monjalon <thomas@monjalon.net> wrote:
>>>
>>>> 28/09/2020 15:53, Ferruh Yigit:
>>>>> On 9/28/2020 10:16 AM, Thomas Monjalon wrote:
>>>>>> 28/09/2020 10:59, Ferruh Yigit:
>>>>>>> On 9/27/2020 4:16 AM, Min Hu (Connor) wrote:
>>>>>>>> From: Huisong Li <lihuisong@huawei.com>
>>>>>>>>
>>>>>>>> Currently, only statistics of rx/tx queues with queue_id less than
>>>>>>>> RTE_ETHDEV_QUEUE_STAT_CNTRS can be displayed. If there is a certain
>>>>>>>> application scenario that it needs to use 256 or more than 256 queues
>>>>>>>> and display all statistics of rx/tx queue. At this moment, we have to
>>>>>>>> change the macro to be equaled to the queue number.
>>>>>>>>
>>>>>>>> However, modifying the macro to be greater than 256 will trigger
>>>>>>>> many errors and warnings from test-pmd, PMD drivers and librte_ethdev
>>>>>>>> during compiling dpdk project. But it is possible and permitted that
>>>>>>>> rx/tx queue number is greater than 256 and all statistics of rx/tx
>>>>>>>> queue need to be displayed. In addition, the data type of rx/tx queue
>>>>>>>> number in rte_eth_dev_configure API is 'uint16_t'. So It is unreasonable
>>>>>>>> to use the 'uint8_t' type for variables that control which per-queue
>>>>>>>> statistics can be displayed.
>>>>>>
>>>>>> The explanation is too much complex and misleading.
>>>>>> You mean you cannot increase RTE_ETHDEV_QUEUE_STAT_CNTRS
>>>>>> above 256 because it is an 8-bit type?
>>>>>>
>>>>>> [...]
>>>>>>>> --- a/lib/librte_ethdev/rte_ethdev.h
>>>>>>>> +++ b/lib/librte_ethdev/rte_ethdev.h
>>>>>>>>      int rte_eth_dev_set_tx_queue_stats_mapping(uint16_t port_id,
>>>>>>>> -		uint16_t tx_queue_id, uint8_t stat_idx);
>>>>>>>> +		uint16_t tx_queue_id, uint16_t stat_idx);
>>>>>> [...]
>>>>>>>>      int rte_eth_dev_set_rx_queue_stats_mapping(uint16_t port_id,
>>>>>>>>      					   uint16_t rx_queue_id,
>>>>>>>> -					   uint8_t stat_idx);
>>>>>>>> +					   uint16_t stat_idx);
>>>>>> [...]
>>>>>>> cc'ed tech-board,
>>>>>>>
>>>>>>> The patch breaks the ethdev ABI without a deprecation notice from previous
>>>>>>> release(s).
>>>>>>>
>>>>>>> It is mainly a fix to the port_id storage type, which we have updated from
>>>>>>> uint8_t to uint16_t in past but some seems remained for
>>>>>>> 'rte_eth_dev_set_tx_queue_stats_mapping()' &
>>>>>>> 'rte_eth_dev_set_rx_queue_stats_mapping()' APIs.
>>>>>>
>>>>>> No, it is not related to the port id, but the number of limited stats.
>>>>>
>>>>> Right, it is not related to the port id, it is fixing the storage type for index
>>>>> used to map the queue stats.
>>>>>>> Since the ethdev library already heavily breaks the ABI this release, I am for
>>>>>>> getting this fix, instead of waiting the fix for one more year.
>>>>>>
>>>>>> If stats can be managed for more than 256 queues, I think it means
>>>>>> it is not limited. In this case, we probably don't need the API
>>>>>> *_queue_stats_mapping which was invented for a limitation of ixgbe.
>>>>>>
>>>>>> The problem is probably somewhere else (in testpmd),
>>>>>> that's why I am against this patch.
>>>>>
>>>>> This patch is not to fix queue stats mapping, I agree there are problems related
>>>>> to it, already shared as comment to this set.
>>>>>
>>>>> But this patch is to fix the build errors when 'RTE_ETHDEV_QUEUE_STAT_CNTRS'
>>>>> needs to set more than 255. Where the build errors seems around the
>>>>> stats_mapping APIs.
>>>>
>>>> It is not said this API is supposed to manage more than 256 queues mapping.
>>>> In general we should not need this API.
>>>> I think it is solving the wrong problem.
>>>
>>>
>>> The original API is a band aid for the limited number of statistics counters
>>> in the Intel IXGBE hardware. It crept into to the DPDK as an API. I would rather
>>> have per-queue statistics and make ixgbe say "not supported"
>>>
>>
>> The current issue is not directly related to '*_queue_stats_mapping' APIs.
>>
>> Problem is not able to set 'RTE_ETHDEV_QUEUE_STAT_CNTRS' > 255.
>> User may need to set the 'RTE_ETHDEV_QUEUE_STAT_CNTRS' > 255, since it is
>> used to define size of the stats counter.
>> "uint64_t q_ipackets[RTE_ETHDEV_QUEUE_STAT_CNTRS];"
>>
>> When 'RTE_ETHDEV_QUEUE_STAT_CNTRS' > 255, it gives multiple build errors,
>> the one in the ethdev is like [1].
>>
>> This can be fixed two ways,
>> a) increase the size of 'stat_idx' storage type to u16 in the
>> '*_queue_stats_mapping' APIs, this is what this patch does.
>> b) Fix with a casting in the comparison, without changing the APIs.
>>
>> I think both are OK, but is (b) more preferable?
> 
> I think the patch (a) is ok, knowing that RTE_ETHDEV_QUEUE_STAT_CNTRS is
> not modified.
> 
> On the substance, I agree with Thomas that the queue_stats_mapping API
> should be replaced by xstats.
> 

This has been discussed in the last technical board meeting, the decision was to 
use xstats to get queue related statistics [2].

But after second look, even if xstats is used to get statistics, 
'RTE_ETHDEV_QUEUE_STAT_CNTRS' is used, since xstats uses 'rte_eth_stats_get()' 
to get queue statistics.
So for the case device has more than 255 queues, 'RTE_ETHDEV_QUEUE_STAT_CNTRS' 
still needs to be set > 255 which will cause the build error.

I have an AR to send a deprecation notice to current method to get the queue 
statistics, and limit the old method to 256 queues. But since xstats is just a 
wrapped to old method, I am not quite sure how deprecating it will work.

@Thomas, @Honnappa, can you give some more insight on the issue?


[2]
https://mails.dpdk.org/archives/dev/2020-October/185299.html

> 
>>
>>
>> [1]
>> ../lib/librte_ethdev/rte_ethdev.c: In function ‘set_queue_stats_mapping’:
>> ../lib/librte_ethdev/rte_ethdev.c:2943:15: warning: comparison is always
>> false due to limited range of data type [-Wtype-limits]
>>   2943 |  if (stat_idx >= RTE_ETHDEV_QUEUE_STAT_CNTRS)
>>        |               ^~


  reply	other threads:[~2020-10-09 20:32 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-31  3:41 [dpdk-dev] [RFC 1/2] Description: lib/ethdev: change data type in tc_rxq and tc_txq Min Hu(Connor)
2020-08-31  3:41 ` [dpdk-dev] [RFC 2/2] Description: dpdk: fix compiling errors for more than 256 per-queue statistics Min Hu(Connor)
2020-09-01  1:33 ` [dpdk-dev] [RFC 1/2] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-01  1:33   ` [dpdk-dev] [RFC 2/2] ethdev: fix compiling errors for per-queue statistics Min Hu (Connor)
2020-09-01  2:23     ` Stephen Hemminger
2020-09-01 11:52   ` [dpdk-dev] [PATCH 0/4] ethdev: change the queue ID type Min Hu (Connor)
2020-09-01 11:52     ` [dpdk-dev] [PATCH 1/4] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-04 11:32       ` [dpdk-dev] [PATCH V2 0/4] ethdev: change the queue ID type Min Hu (Connor)
2020-09-04 11:32         ` [dpdk-dev] [PATCH V2 1/4] ethdev: fix compiling errors for per-queue statistics Min Hu (Connor)
2020-09-04 18:04           ` Ferruh Yigit
2020-09-04 18:31           ` Ferruh Yigit
2020-09-05 16:51             ` Thomas Monjalon
2020-09-23  2:31             ` Min Hu (Connor)
2020-09-23  9:18               ` Ferruh Yigit
2020-09-25  8:58                 ` Min Hu (Connor)
2020-09-25  9:36                   ` Ferruh Yigit
2020-09-23 12:59           ` [dpdk-dev] [PATCH V3 0/4] change data type in TC queue Min Hu (Connor)
2020-09-23 12:59             ` [dpdk-dev] [PATCH V3 1/4] dpdk: fix compiling errors for per-queue statistics Min Hu (Connor)
2020-09-23 13:00             ` [dpdk-dev] [PATCH V3 2/4] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-23 13:00             ` [dpdk-dev] [PATCH V3 3/4] doc: announce modified field in DCB TC queue mapping Min Hu (Connor)
2020-09-23 13:00             ` [dpdk-dev] [PATCH V3 4/4] doc: announce modified in queue stats mapping API Min Hu (Connor)
2020-09-25  9:41             ` [dpdk-dev] [PATCH V3 0/4] change data type in TC queue Ferruh Yigit
2020-09-04 11:32         ` [dpdk-dev] [PATCH V2 2/4] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-04 11:32         ` [dpdk-dev] [PATCH V2 3/4] doc: announce modified field in DCB TC queue mapping Min Hu (Connor)
2020-09-04 11:32         ` [dpdk-dev] [PATCH V2 4/4] doc: announce modified field in ethdev API Min Hu (Connor)
2020-09-04 14:33         ` [dpdk-dev] [PATCH V2 0/4] ethdev: change the queue ID type Ferruh Yigit
2020-09-09 12:36       ` [dpdk-dev] [PATCH V3 0/3] add FEC support Min Hu (Connor)
2020-09-09 12:36         ` [dpdk-dev] [PATCH V3 1/3] ethdev: introduce FEC API Min Hu (Connor)
2020-09-09 12:36         ` [dpdk-dev] [PATCH V3 2/3] net/hns3: support FEC Min Hu (Connor)
2020-09-09 12:36         ` [dpdk-dev] [PATCH V3 3/3] app/testpmd: add FEC command Min Hu (Connor)
2020-09-01 11:52     ` [dpdk-dev] [PATCH 2/4] ethdev: fix compiling errors for per-queue statistics Min Hu (Connor)
2020-09-01 16:17       ` Ferruh Yigit
2020-09-01 11:52     ` [dpdk-dev] [PATCH 3/4] doc: announce modified field in DCB TC queue mapping Min Hu (Connor)
2020-09-01 11:52     ` [dpdk-dev] [PATCH 4/4] doc: announce modified field in ethdev API Min Hu (Connor)
2020-09-01 16:14     ` [dpdk-dev] [PATCH 0/4] ethdev: change the queue ID type Ferruh Yigit
2020-09-25 12:51 ` [dpdk-dev] [PATCH V4 0/2] change data type in TC queue Min Hu (Connor)
2020-09-25 12:51   ` [dpdk-dev] [PATCH V4 1/2] dpdk: resolve compiling errors for per-queue stats Min Hu (Connor)
2020-09-25 12:51   ` [dpdk-dev] [PATCH V4 2/2] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-25 13:14   ` [dpdk-dev] [PATCH V4 0/2] change data type in TC queue Ferruh Yigit
2020-09-27  3:16 ` [dpdk-dev] [PATCH V5 " Min Hu (Connor)
2020-09-27  3:16   ` [dpdk-dev] [PATCH V5 1/2] dpdk: resolve compiling errors for per-queue stats Min Hu (Connor)
2020-09-28  8:59     ` Ferruh Yigit
2020-09-28  9:16       ` [dpdk-dev] [dpdk-techboard] " Thomas Monjalon
2020-09-28 12:00         ` Ananyev, Konstantin
2020-09-28 13:47         ` Min Hu (Connor)
2020-09-28 15:35           ` Thomas Monjalon
2020-09-28 13:53         ` Ferruh Yigit
2020-09-28 15:24           ` Thomas Monjalon
2020-09-28 15:43             ` Stephen Hemminger
2020-10-05 12:23               ` Ferruh Yigit
2020-10-06  8:33                 ` Olivier Matz
2020-10-09 20:32                   ` Ferruh Yigit [this message]
2020-10-10  8:09                     ` Thomas Monjalon
2020-10-12 17:02                       ` Ferruh Yigit
2020-09-29  4:49           ` Min Hu (Connor)
2020-09-29  9:33             ` Thomas Monjalon
2020-09-29 13:46               ` Min Hu (Connor)
2020-09-28 11:52       ` Ananyev, Konstantin
2020-09-30  8:34       ` [dpdk-dev] " Kinsella, Ray
2020-09-27  3:16   ` [dpdk-dev] [PATCH V5 2/2] ethdev: change data type in TC rxq and TC txq Min Hu (Connor)
2020-09-28  9:04     ` Ferruh Yigit
2020-09-28  9:21       ` [dpdk-dev] [dpdk-techboard] " Thomas Monjalon
2020-10-05 12:26         ` Ferruh Yigit
2020-10-06 12:04           ` Ferruh Yigit

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