On 2021-01-20 15:54, Toke Høiland-Jørgensen wrote:
Björn Töpel <bjorn.topel@xxxxxxxxx> writes:
On 2021-01-20 13:50, Toke Høiland-Jørgensen wrote:
Björn Töpel <bjorn.topel@xxxxxxxxx> writes:
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c001766adcbc..bbc7d9a57262 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3836,6 +3836,12 @@ union bpf_attr {
* Return
* A pointer to a struct socket on success or NULL if the file is
* not a socket.
+ *
+ * long bpf_redirect_xsk(struct xdp_buff *xdp_md, u64 action)
+ * Description
+ * Redirect to the registered AF_XDP socket.
+ * Return
+ * **XDP_REDIRECT** on success, otherwise the action parameter is returned.
*/
I think it would be better to make the second argument a 'flags'
argument and make values > XDP_TX invalid (like we do in
bpf_xdp_redirect_map() now). By allowing any value as return you lose
the ability to turn it into a flags argument later...
Yes, but that adds a run-time check. I prefer this non-checked version,
even though it is a bit less futureproof.
That...seems a bit short-sighted? :)
Can you actually see a difference in your performance numbers?
I would rather add an additional helper *if* we see the need for flags,
instead of paying for that upfront. For me, BPF is about being able to
specialize, and not having one call with tons of checks.
(Related; Going forward, the growing switch() for redirect targets in
xdp_do_redirect() is a concern for me...)
And yes, even with all those fancy branch predictors, less instructions
is still less. :-) (It shows in my ubenchs.)
Björn
