On Mon, Mar 24, 2014 at 10:59:06AM -0700, Jarno Rajahalme wrote:
> This patch shrinks the struct ofpbuf from 104 to 48 bytes on 64-bit
> systems, or from 52 to 36 bytes on 32-bit systems (counting in the
> 'l7' removal by the previous patch). This may help contribute to
> cache efficiency, and will speed up initializing, copying and
> manipulating ofpbufs. This is potentially important for the DPDK
> datapath, but the rest of the code base may also see a little benefit.
>
> Changes are:
>
> - Remove 'l7' pointer (previous patch).
> - Use offsets instead of layer pointers for l2_5, l3, and l4 using
> 'l2' as basis. Usually 'data' is the same as 'l2', but this is not
> always the case (e.g., when parsing or constructing a packet), so it
> can not be easily used as the offset basis. Also, packet parsing is
> faster if we do not need to maintain the offsets each time we pull
> data from the ofpbuf.
> - Use uint32_t for 'allocated' and 'size', as 2^32 is enough even for
> largest possible messages/packets.
> - Use packed enum for 'source'.
> - Rearrange to avoid unnecessary padding.
> - Remove 'private_p', which was used only in two cases, both of which
> had the invariant ('l2' == 'data'), so we can temporarily use 'l2'
> as a private pointer.
>
> Signed-off-by: Jarno Rajahalme <[email protected]>
ofpbuf_resize_l2() and ofpbuf_resize_l2_5() look kind of big to me for
inlining.
ofpbuf_resize_l2() looks rather redundant with ofpbuf_resize_l2_5().
I think it could be written as:
static inline void * ofpbuf_resize_l2(struct ofpbuf *b, int increment)
{
ofpbuf_resize_l2_5(b, increment);
OFPBUF_ADJUST_LAYER_OFFSET(b, l2_5, increment);
return b->l2;
}
I don't think OFPBUF_ADJUST_LAYER_OFFSET() really needs to be a macro,
e.g.:
static inline void
ofpbuf_adjust_layer_offset(uint16_t *offset, int increment)
{
if (*offset != UINT16_MAX) {
*offset += increment;
}
}
Acked-by: Ben Pfaff <[email protected]>
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