netdev - Re: [PATCH bpf-next v6 10/12] samples/bpf: add buffer recycling for unaligned chunks to xdpsock

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Message-ID: <CDECD1EE-EFE2-421A-94B9-3BAF1128D5EC@gmail.com>
Date:   Fri, 30 Aug 2019 08:49:57 -0700
From:   "Jonathan Lemon" <jonathan.lemon@...il.com>
To:     "Kevin Laatz" <kevin.laatz@...el.com>
Cc:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        bjorn.topel@...el.com, magnus.karlsson@...el.com,
        jakub.kicinski@...ronome.com, saeedm@...lanox.com,
        maximmi@...lanox.com, stephen@...workplumber.org,
        bruce.richardson@...el.com, ciara.loftus@...el.com,
        bpf@...r.kernel.org, intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH bpf-next v6 10/12] samples/bpf: add buffer recycling for
 unaligned chunks to xdpsock



On 26 Aug 2019, at 19:25, Kevin Laatz wrote:

> This patch adds buffer recycling support for unaligned buffers. Since we
> don't mask the addr to 2k at umem_reg in unaligned mode, we need to make
> sure we give back the correct (original) addr to the fill queue. We achieve
> this using the new descriptor format and associated masks. The new format
> uses the upper 16-bits for the offset and the lower 48-bits for the addr.
> Since we have a field for the offset, we no longer need to modify the
> actual address. As such, all we have to do to get back the original address
> is mask for the lower 48 bits (i.e. strip the offset and we get the address
> on it's own).
>
> Signed-off-by: Kevin Laatz <kevin.laatz@...el.com>
> Signed-off-by: Bruce Richardson <bruce.richardson@...el.com>
Acked-by: Jonathan Lemon <jonathan.lemon@...il.com>