Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id and sender_cpu

From	Jason Wang <jasowang@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id and sender_cpu
Date	2016-04-01 06:50 +0200
Message-ID	<riZbY-7Gh-5@gated-at.bofh.it> (permalink)
References	<riDOa-iF-3@gated-at.bofh.it> <riDOa-iF-7@gated-at.bofh.it> <riIb9-3Af-39@gated-at.bofh.it> <riWQO-62F-13@gated-at.bofh.it> <riXtx-6ie-9@gated-at.bofh.it>
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On 04/01/2016 10:55 AM, Eric Dumazet wrote:
> On Fri, 2016-04-01 at 10:13 +0800, Jason Wang wrote:
>
>
>> The problem is we want to support busy polling for tun. This needs
>> napi_id to be passed to tun socket by sk_mark_napi_id() during
>> tun_net_xmit(). But before reaching this, XPS will set sender_cpu will
>> make us can't see correct napi_id.
>>
> Looks like napi_id should have precedence then ?

But then when busy polling is enabled, we may still hit the issue before
commit 2bd82484bb4c5db1d5dc983ac7c409b2782e0154? So looks like sometimes
(e.g for tun), we need both two fields.

>
> Only forwarding should allow the field to be cleared to allow XPS to do
> its job.
>
> Maybe skb_sender_cpu_clear() was removed too early (commit
> 64d4e3431e686dc37ce388ba531c4c4e866fb141)

Not sure I get you, but this will clear napi_id too.

> Look, it is 8pm here, I am pretty sure a solution can be found,
> but I am also need to take a break, I started at 3am today...
>
>
>

Thread

[PATCH net-next 1/6] net: skbuff: don't use union for napi_id and sender_cpu Jason Wang <jasowang@redhat.com> - 2016-03-31 08:00 +0200
  Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id  and sender_cpu Eric Dumazet <eric.dumazet@gmail.com> - 2016-03-31 12:40 +0200
    Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id  and sender_cpu David Miller <davem@davemloft.net> - 2016-03-31 22:10 +0200
      Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id and  sender_cpu Jason Wang <jasowang@redhat.com> - 2016-04-01 04:50 +0200
    Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id and  sender_cpu Jason Wang <jasowang@redhat.com> - 2016-04-01 04:20 +0200
      Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id  and sender_cpu Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-01 05:00 +0200
        Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id and  sender_cpu Jason Wang <jasowang@redhat.com> - 2016-04-01 06:50 +0200
          Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id  and sender_cpu Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-01 15:10 +0200

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