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xdp: base API for new XDP rx-queue info concept

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This patch only introduce the core data structures and API functions.
All XDP enabled drivers must use the API before this info can used.

There is a need for XDP to know more about the RX-queue a given XDP
frames have arrived on.  For both the XDP bpf-prog and kernel side.

Instead of extending xdp_buff each time new info is needed, the patch
creates a separate read-mostly struct xdp_rxq_info, that contains this
info.  We stress this data/cache-line is for read-only info.  This is
NOT for dynamic per packet info, use the data_meta for such use-cases.

The performance advantage is this info can be setup at RX-ring init
time, instead of updating N-members in xdp_buff.  A possible (driver
level) micro optimization is that xdp_buff->rxq assignment could be
done once per XDP/NAPI loop.  The extra pointer deref only happens for
program needing access to this info (thus, no slowdown to existing
use-cases).

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jesper Dangaard Brouer
2018-01-03 11:25:13 +01:00
committed by Alexei Starovoitov
parent 5f103c5d4d
commit aecd67b607
4 changed files with 117 additions and 1 deletions
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2
include/linux/filter.h
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@@ -20,6 +20,7 @@
#include <linux/set_memory.h>
#include <linux/kallsyms.h>
#include <net/xdp.h>
#include <net/sch_generic.h>
#include <uapi/linux/filter.h>
@@ -503,6 +504,7 @@ struct xdp_buff {
void *data_end;
void *data_meta;
void *data_hard_start;
struct xdp_rxq_info *rxq;
};
/* Compute the linear packet data range [data, data_end) which