On 2023/10/3 12:27, John Fastabend wrote:
Liu Jian wrote:
If the sockmap msg redirection function is used only to forward packets
and no other operation, the execution result of the BPF_SK_MSG_VERDICT
program is the same each time. In this case, the BPF program only needs to
be run once. Add BPF_F_PERMANENT flag to bpf_msg_redirect_map() and
bpf_msg_redirect_hash() to implement this ability.
Then we can enable this function in the bpf program as follows:
bpf_msg_redirect_hash(xx, xx, xx, BPF_F_INGRESS | BPF_F_PERMANENT);
Test results using netperf TCP_STREAM mode:
for i in 1 64 128 512 1k 2k 32k 64k 100k 500k 1m;then
netperf -T 1,2 -t TCP_STREAM -H 127.0.0.1 -l 20 -- -m $i -s 100m,100m -S 100m,100m
done
before:
3.84 246.52 496.89 1885.03 3415.29 6375.03 40749.09 48764.40 51611.34 55678.26 55992.78
after:
4.43 279.20 555.82 2080.79 3870.70 7105.44 41836.41 49709.75 51861.56 55211.00 54566.85
Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
---
First sorry for the delay I was thinking about this a bit. I decided it likely makes
a lot of sense if you want to build an l7 load balancer where you just read some
keys off an initial msg and then pin the rest of the connection to a specific
backend or proxy socket, etc.
include/linux/skmsg.h | 1 +
include/uapi/linux/bpf.h | 45 ++++++++++++++++++++++++++--------
net/core/skmsg.c | 6 ++++-
net/core/sock_map.c | 4 +--
net/ipv4/tcp_bpf.c | 12 +++++----
tools/include/uapi/linux/bpf.h | 45 ++++++++++++++++++++++++++--------
6 files changed, 85 insertions(+), 28 deletions(-)
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index c1637515a8a4..acd7de85608b 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -83,6 +83,7 @@ struct sk_psock {
u32 cork_bytes;
u32 eval;
bool redir_ingress; /* undefined if sk_redir is null */
+ bool redir_permanent;
struct sk_msg *cork;
struct sk_psock_progs progs;
#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 70bfa997e896..cec6c34f4486 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3029,11 +3029,23 @@ union bpf_attr {
* socket level. If the message *msg* is allowed to pass (i.e. if
* the verdict eBPF program returns **SK_PASS**), redirect it to
* the socket referenced by *map* (of type
- * **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
- * egress interfaces can be used for redirection. The
- * **BPF_F_INGRESS** value in *flags* is used to make the
- * distinction (ingress path is selected if the flag is present,
- * egress path otherwise). This is the only flag supported for now.
+ * **BPF_MAP_TYPE_SOCKMAP**) at index *key*.
+ *
+ * The following *flags* are supported:
+ *
+ * **BPF_F_INGRESS**
+ * Both ingress and egress interfaces can be used for redirection.
+ * The **BPF_F_INGRESS** value in *flags* is used to make the
+ * distinction. Ingress path is selected if the flag is present,
+ * egress path otherwise.
+ * **BPF_F_PERMANENT**
+ * Indicates that redirect verdict and the target socket should be
+ * remembered. The verdict program will not be run for subsequent
+ * packets, unless an error occurs when forwarding packets.
Why clear it on error? The error is almost always because either the socket is
being torn down or there is a memory ENOMEM error that is going to be kicked
back to user.
Sorry, yes, you're right, I've changed the code, but forgot to change
the help document. Have sent next version to fix this. Thank you~.
Is the idea that you can try anopther backend possibly by picking another socket
out of the table? But, I'm not sure how that might work because you probably
don't know that this is even the beginning of a msg block.
I'm wondering if I missed some other reason or if its just simpler to pass the
error up the stack and keep the same sk_redir.
Thanks,
John
