On 21/03/2023 19.45, Stanislav Fomichev wrote:
On Tue, Mar 21, 2023 at 6:32 AM Jesper Dangaard Brouer
<jbrouer@xxxxxxxxxx> wrote:
On 17/03/2023 22.13, Stanislav Fomichev wrote:
On 03/17, Jesper Dangaard Brouer wrote:
When driver developers add XDP-hints kfuncs for RX hash it is
practical to print the return code in bpf_printk trace pipe log.
Print hash value as a hex value, both AF_XDP userspace and bpf_prog,
as this makes it easier to spot poor quality hashes.
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
(with a small suggestion below, maybe can do separately?)
---
.../testing/selftests/bpf/progs/xdp_hw_metadata.c | 9 ++++++---
tools/testing/selftests/bpf/xdp_hw_metadata.c | 5 ++++-
2 files changed, 10 insertions(+), 4 deletions(-)
[...]
diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c
b/tools/testing/selftests/bpf/xdp_hw_metadata.c
index 400bfe19abfe..f3ec07ccdc95 100644
--- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
@@ -3,6 +3,9 @@
/* Reference program for verifying XDP metadata on real HW.
Functional test
* only, doesn't test the performance.
*
[..]
+ * BPF-prog bpf_printk info outout can be access via
+ * /sys/kernel/debug/tracing/trace_pipe
Maybe we should just dump the contents of
/sys/kernel/debug/tracing/trace for every poll cycle?
I think this belongs to a separate patch.
SG. If you prefer to keep the comment let's also s/outout/outPut/.
Sorry, missed this... will fix in V3
We can also maybe enable tracing in this program transparently?
I usually forget 'echo 1 >
/sys/kernel/debug/tracing/events/bpf_trace/bpf_trace_printk/enable'
myself :-)
What is this trick?
On the recent kernels I think this event has to be explicitly enabled
for bpf_prink() to work? Not sure.
The output still work for me then I have zero in
/sys/kernel/debug/tracing/events/bpf_trace/bpf_trace_printk/enable
That's why having something like enable_tracing() and dump_trace()
here might be helpful for whoever is running the prog.
