netdev - Re: [PATCH net-next] net: use bigger pages in __netdev_alloc

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Date:	Wed, 26 Sep 2012 09:36:22 -0700
From:	Alexander Duyck <alexander.h.duyck@...el.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net: use bigger pages in __netdev_alloc_frag

On 09/26/2012 09:14 AM, Eric Dumazet wrote:
> On Wed, 2012-09-26 at 09:00 -0700, Alexander Duyck wrote:
>
>> One minor thought.  Instead of tracking offset and size why not just
>> work from the top down instead of the bottom up?
>>
>> So instead of starting with the frag offset at 0, why not start it at
>> PAGE_SIZE << order, and then work your way down to 0.  That way you
>> don't need to track both size and offset.
>>
> How do you refill then ? 
>
> (ie setting xxx->offset back to PAGE_SIZE << order)
>
> I am not sure we have direct access to a page order given a struct page
> pointer.
>
> I also like struct page_frag abstraction, because it might allow us
> better code factorization with other frag allocators.
>
> ( skb_append_datato_frags(), sk_page_frag_refill(), ...)

I forgot about the page recycling portion of it.  I was still thinking
of the original implementation that had a fixed page order.  You are
correct, with the page order being dynamic you will have to store size
somewhere.

Thanks,

Alex




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