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From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
	Chenbo Xia <chenbo.xia@intel.com>,
	Shreyansh Jain <shreyansh.jain@nxp.com>,
	Remy Horton <remy.horton@intel.com>,
	Ferruh Yigit <ferruh.yigit@intel.com>,
	Thomas Monjalon <thomas@monjalon.net>
Cc: dev@dpdk.org, Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>,
	stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] net/virtio: remove handling of zero desc number on RxQ setup
Date: Tue, 14 Sep 2021 10:33:40 +0300	[thread overview]
Message-ID: <b860cbb9-9109-6a03-6d9e-bd004808dfcf@oktetlabs.ru> (raw)
In-Reply-To: <17b58919-03a7-db3b-0c2d-612b3f365768@redhat.com>

On 9/14/21 10:26 AM, Maxime Coquelin wrote:
> 
> 
> On 9/14/21 8:40 AM, Andrew Rybchenko wrote:
>> On 9/13/21 10:25 PM, Maxime Coquelin wrote:
>>>
>>>
>>> On 8/20/21 2:47 PM, Andrew Rybchenko wrote:
>>>> From: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
>>>>
>>>> Rx queue setup callback allows to use the whole ring when
>>>> descriptor number argument equals zero. There's no point to
>>>> handle zero in any way since RTE Rx queue setup function
>>>> rte_eth_rx_queue_setup() doesn't pass zero using fallback
>>>> values.
>>>>
>>>> Fixes: 3be82f5cc5e3 ("ethdev: support PMD-tuned Tx/Rx parameters")
>>>> Cc: stable@dpdk.org
>>>>
>>>> Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
>>>> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
>>>> ---
>>>>  drivers/net/virtio/virtio_rxtx.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
>>>> index 8a48fba5cc..18f03c9fc9 100644
>>>> --- a/drivers/net/virtio/virtio_rxtx.c
>>>> +++ b/drivers/net/virtio/virtio_rxtx.c
>>>> @@ -706,7 +706,7 @@ virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
>>>>  	}
>>>>  	vq->vq_free_thresh = rx_free_thresh;
>>>>  
>>>> -	if (nb_desc == 0 || nb_desc > vq->vq_nentries)
>>>> +	if (nb_desc > vq->vq_nentries)
>>>>  		nb_desc = vq->vq_nentries;
>>>>  	vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);
>>>>  
>>>>
>>>
>>> Is that really a fix?
>>> I see it more like an optimization in a cold path, so maybe it is not
>>> worth backporting?
>>
>> The main idea is not an optimization, but simplification of
>> the code to make it easier to understand. Less special
>> cases is better.
>>
>> I agree that it does not make sense to backport it.
> 
> Ok, thanks. I'll will remove the Fixes tag while applying, no need to
> resubmit.

Thanks,
Andrew.

> Maxime
>>
>>> Other than that:
>>> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>
>> Thanks,
>> Andrew.
>>


  reply	other threads:[~2021-09-14  7:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20 12:47 Andrew Rybchenko
2021-09-13 19:25 ` Maxime Coquelin
2021-09-14  6:40   ` Andrew Rybchenko
2021-09-14  7:26     ` Maxime Coquelin
2021-09-14  7:33       ` Andrew Rybchenko [this message]
2021-09-14 11:24 ` Maxime Coquelin

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