netdev - Re: [PATCH net-next 2/2] virtio-net: get rid of unnecessary container of rq stats

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Date:   Wed, 1 Aug 2018 10:46:53 +0900
From:   Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:     Jason Wang <jasowang@...hat.com>
Cc:     mst@...hat.com, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 2/2] virtio-net: get rid of unnecessary container
 of rq stats

On 2018/08/01 10:39, Jason Wang wrote:
> On 2018年07月31日 18:02, Toshiaki Makita wrote:
>> On 2018/07/31 18:43, Jason Wang wrote:
>>> We don't maintain tx counters in rx stats any more. There's no need
>>> for an extra container of rq stats.
>>>
>>> Cc: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
>>> Signed-off-by: Jason Wang <jasowang@...hat.com>
>>> ---
>>>   drivers/net/virtio_net.c | 80
>>> ++++++++++++++++++++++--------------------------
>>>   1 file changed, 36 insertions(+), 44 deletions(-)
>>>
>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>>> index 72d3f68..14f661c 100644
>>> --- a/drivers/net/virtio_net.c
>>> +++ b/drivers/net/virtio_net.c
>>> @@ -87,7 +87,8 @@ struct virtnet_sq_stats {
>>>       u64 kicks;
>>>   };
>>>   -struct virtnet_rq_stat_items {
>>> +struct virtnet_rq_stats {
>>> +    struct u64_stats_sync syncp;
>>>       u64 packets;
>>>       u64 bytes;
>>>       u64 drops;
>>> @@ -98,17 +99,8 @@ struct virtnet_rq_stat_items {
>>>       u64 kicks;
>>>   };
>>>   -struct virtnet_rq_stats {
>>> -    struct u64_stats_sync syncp;
>>> -    struct virtnet_rq_stat_items items;
>>> -};
>> I'm not thinking removing sq stat is needed but even if it is I want to
>> keep virtnet_rq_stats to avoid allocating unnecessary u64_stats_syncp on
>> stack in virtnet_receive. I would just remove virtnet_rx_stats if
>> necessary.
> 
> It's a nop on 64bit machines. And an unsigned on 32bit. So it's overhead
> could be ignored I think.

It's not a big problem so that's OK. I just felt like you reverted
unnecessarily too much. Anyway it is already applied and I'm not
thinking of changing this any more.

-- 
Toshiaki Makita