netdev - Re: [net-next] tcp: allow drivers to tweak TSQ logic

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Date:   Sat, 11 Nov 2017 15:27:19 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Toke Høiland-Jørgensen <toke@...e.dk>,
        Kir Kolyshkin <kir@...nvz.org>
Subject: Re: [net-next] tcp: allow drivers to tweak TSQ logic

Thanks Eric!

> We expect wifi drivers to set this field to smaller values (tests have
> been done with values from 6 to 9)

I suppose we should test each driver or so.

> They would have to use following template :
> 
> if (skb->sk && skb->sk->sk_pacing_shift != MY_PACING_SHIFT)
>      skb->sk->sk_pacing_shift = MY_PACING_SHIFT;

Hm. I wish we wouldn't have to do this on every skb, but perhaps it
doesn't matter that much.

>  	u16			sk_gso_max_segs;
> +	u8			sk_pacing_shift;

I guess you tried to fill a hole, but weren't we saying that it would
be better in the same cacheline? Then again, perhaps both cachelines
are resident anyway, haven't looked at this now.

Unrelated to that, I think this is missing a documentation update since
the struct has kernel-doc comments.

johannes