netdev - Re: [net-next PATCH v3 4/6] udp: Partially unroll handling of first segment and last segment

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Message-ID: <CAF=yD-JD=WCULdj_u0xjj3S9BDcbHhSCkWXCLHMx04U+Jgz55A@mail.gmail.com>
Date:   Mon, 7 May 2018 14:57:39 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        David Miller <davem@...emloft.net>
Subject: Re: [net-next PATCH v3 4/6] udp: Partially unroll handling of first
 segment and last segment

On Mon, May 7, 2018 at 2:08 PM, Alexander Duyck
<alexander.duyck@...il.com> wrote:
> From: Alexander Duyck <alexander.h.duyck@...el.com>
>
> This patch allows us to take care of unrolling the first segment and the
> last segment of the loop for processing the segmented skb. Part of the
> motivation for this is that it makes it easier to process the fact that the
> first fame and all of the frames in between should be mostly identical
> in terms of header data, and the last frame has differences in the length
> and partial checksum.
>
> In addition I am dropping the header length calculation since we don't
> really need it for anything but the last frame and it can be easily
> obtained by just pulling the data_len and offset of tail from the transport
> header.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>

I'm not a fan of the more complicated control flow, as I pointed out
before. It only seems to save one assignment to uh from segs.

Both follow-up patches are now more complex, because they need
to add the same code in two locations.