netdev - Re: [PATCH RFC v2 02/12] sock: skb_copy_ubufs support for compound pages

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Message-ID: <CAF=yD-KDH+pMjrbhP+nkD=JGwFNXL8EOHrxAGJYH=iQeLibOyw@mail.gmail.com>
Date:   Wed, 22 Feb 2017 20:51:57 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH RFC v2 02/12] sock: skb_copy_ubufs support for compound pages

>>
>> -             page = alloc_page(gfp_mask);
>> +             page = skb_frag_page(f);
>> +             if (page_count(page) == 1) {
>> +                     skb_frag_ref(skb, i);
>
> This could be : get_page(page);

Ah, indeed. Thanks.

>
>> +                     goto copy_done;
>> +             }
>> +
>> +             if (f->size > PAGE_SIZE) {
>> +                     order = get_order(f->size);
>> +                     mask |= __GFP_COMP;
>
> Note that this would probably fail under memory pressure.
>
> We could instead try to explode the few segments into order-0 only
> pages.

Good point. I'll revise to use only order-0 here.