[dpdk-stable] [PATCH] net/virtio: remove handling of zero desc number on RxQ setup
Andrew Rybchenko
andrew.rybchenko at oktetlabs.ru
Tue Sep 14 09:33:40 CEST 2021
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 at 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 at dpdk.org
>>>>
>>>> Signed-off-by: Ivan Ilchenko <ivan.ilchenko at oktetlabs.ru>
>>>> Signed-off-by: Andrew Rybchenko <andrew.rybchenko at 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 at redhat.com>
>>
>> Thanks,
>> Andrew.
>>
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