2020-02-18 08:46 UTC+0100 ~ Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
The performance of bpf_redirect() is now roughly the same as that of
bpf_redirect_map(). However, David Ahern pointed out that the header file
has not been updated to reflect this, and still says that a significant
performance increase is possible when using bpf_redirect_map(). Remove this
text from the bpf_redirect_map() description, and reword the description in
bpf_redirect() slightly.
Fixes: 1d233886dd90 ("xdp: Use bulking for non-map XDP_REDIRECT and consolidate code paths")
Suggested-by: David Ahern <dsahern@xxxxxxxxx>
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
include/uapi/linux/bpf.h | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f1d74a2bd234..7a526d917fb3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1045,9 +1045,9 @@ union bpf_attr {
* supports redirection to the egress interface, and accepts no
* flag at all.
*
- * The same effect can be attained with the more generic
- * **bpf_redirect_map**\ (), which requires specific maps to be
- * used but offers better performance.
+ * The same effect can also be attained with the more generic
+ * **bpf_redirect_map**\ (), which uses a BPF map to store the
+ * redirect target instead of providing it directly to the helper.
* Return
* For XDP, the helper returns **XDP_REDIRECT** on success or
* **XDP_ABORTED** on error. For other program types, the values
@@ -1610,12 +1610,6 @@ union bpf_attr {
* one of the XDP program return codes up to XDP_TX, as chosen by
* the caller. Any higher bits in the *flags* argument must be
* unset.
- *
- * When used to redirect packets to net devices, this helper
- * provides a high performance increase over **bpf_redirect**\ ().
- * This is due to various implementation details of the underlying
- * mechanisms, one of which is the fact that **bpf_redirect_map**\
- * () tries to send packet as a "bulk" to the device.
* Return
* **XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
*
We could maybe leave something like “See also bpf_redirect()" in the
description of "bpf_redirect_map()"?
Either way,
Reviewed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Thanks,
Quentin
