Re: [PATCH 16/40] netvm: hook skb allocation to reserves

["Arnaldo Carvalho de Melo" <acme@ghostprotocols.net>]

On 5/4/07, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> Change the skb allocation api to indicate RX usage and use this to fall back to
> the reserve when needed. Skbs allocated from the reserve are tagged in
> skb->emergency.
>
> Teach all other skb ops about emergency skbs and the reserve accounting.
>
> Use the (new) packet split API to allocate and track fragment pages from the
> emergency reserve. Do this using an atomic counter in page->index. This is
> needed because the fragments have a different sharing semantic than that
> indicated by skb_shinfo()->dataref.
>
> (NOTE the extra atomic overhead is only for those pages allocated from the
> reserves - it does not affect the normal fast path.)
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
>  include/linux/skbuff.h |   22 +++++-
>  net/core/skbuff.c      |  161 ++++++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 157 insertions(+), 26 deletions(-)

> +#define skb_alloc_rx(skb) (skb_emergency(skb) ? SKB_ALLOC_RX : 0)

skb_alloc_rx seems to imply "alloc an skb for rx", not "gimme the
right flags to allocate a skb for rx". Can this be changed to
"skb_alloc_rx_flag(skb)", similar to the existing sock_flag() for
socks?

- Arnaldo
-
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