Re: [PATCH bpf-next v2 2/2] samples/bpf: Add xdp_sample_pkts example

David Beckett [off-list ref] writes:

On 04/06/18 17:33, Toke Høiland-Jørgensen wrote:

quoted

+
+#define SAMPLE_SIZE 64ul
+

The program currently cannot sample minimum sized packets, as the 4 Byte 
crc checksum isnt present in ctx,
may be better to use 60ul sample size to allow for these packets to be 
processed?

Right. However, this also reminds me that I wanted to make the sampling
size dynamic, so it is possible to dump packets that are smaller than
the configured SAMPLE_SIZE. Will fix :)

quoted

+	if (data + SAMPLE_SIZE < data_end) {
+		/* The XDP perf_event_output handler will use the upper 32 bits
+		 * of the flags argument as a number of bytes to include of the

I may be wrong on this but should this also be <= to allow for packets 
at SAMPLE_SIZE to be sampled?

Yes, you are right, but that goes away with the change I mentioned above.

-Toke