On Mon, Dec 09, 2019 at 08:56:19AM +0100, Magnus Karlsson wrote: > Currently, the xsk ring code has two cached producer pointers: > prod_head and prod_tail. This patch consolidates these two into a > single one called cached_prod to make the code simpler and easier to > maintain. This will be in line with the user space part of the the > code found in libbpf, that only uses a single cached pointer. > > The Rx path only uses the two top level functions > xskq_produce_batch_desc and xskq_produce_flush_desc and they both use > prod_head and never prod_tail. So just move them over to > cached_prod. > > The Tx XDP_DRV path uses xskq_produce_addr_lazy and > xskq_produce_flush_addr_n and unnecessarily operates on both prod_tail > and prod_cons, so move them over to just use cached_prod by skipping prod_cons or prod_head? > the intermediate step of updating prod_tail. > > The Tx path in XDP_SKB mode uses xskq_reserve_addr and > xskq_produce_addr. They currently use both cached pointers, but we can > operate on the global producer pointer in xskq_produce_addr since it > has to be updated anyway, thus eliminating the use of both cached > pointers. We can also remove the xskq_nb_free in xskq_produce_addr > since it is already called in xskq_reserve_addr. No need to do it > twice. > > When there is only one cached producer pointer, we can also simplify > xskq_nb_free by removing one argument.
