On 21/03/2023 19.47, Stanislav Fomichev wrote:
On Tue, Mar 21, 2023 at 6:47 AM Jesper Dangaard Brouer <brouer@xxxxxxxxxx> 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> --- .../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/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c index 40c17adbf483..ce07010e4d48 100644 --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c @@ -77,10 +77,13 @@ int rx(struct xdp_md *ctx) meta->rx_timestamp = 0; /* Used by AF_XDP as not avail signal */ } - if (!bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash)) - bpf_printk("populated rx_hash with %u", meta->rx_hash); - else + ret = bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash); + if (ret >= 0) { + bpf_printk("populated rx_hash with 0x%08X", meta->rx_hash); + } else { + bpf_printk("rx_hash not-avail errno:%d", ret); meta->rx_hash = 0; /* Used by AF_XDP as not avail signal */ + } return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS); } 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_pipes/outout/output/
Fixed in V3
But let's maybe drop it? If you want to make it more usable, let's have a separate patch to enable tracing and periodically dump it to the console instead (as previously discussed).
Cat'ing /sys/kernel/debug/tracing/trace_pipe work for me regardless of setting in /sys/kernel/debug/tracing/events/bpf_trace/bpf_trace_printk/enable We likely need a followup patch that adds a BPF config switch that can disable bpf_printk calls, because this adds overhead and thus affects the timestamps.
With this addressed: Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>+ * * RX: * - UDP 9091 packets are diverted into AF_XDP * - Metadata verified: @@ -156,7 +159,7 @@ static void verify_xdp_metadata(void *data, clockid_t clock_id) meta = data - sizeof(*meta); - printf("rx_hash: %u\n", meta->rx_hash); + printf("rx_hash: 0x%08X\n", meta->rx_hash); printf("rx_timestamp: %llu (sec:%0.4f)\n", meta->rx_timestamp, (double)meta->rx_timestamp / NANOSEC_PER_SEC); if (meta->rx_timestamp) {
