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

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Message-ID: <1459479325.6473.260.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Thu, 31 Mar 2016 19:55:25 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	davem@...emloft.net, mst@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/6] net: skbuff: don't use union for napi_id
 and sender_cpu

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 ?

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)

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...