On Fri, Dec 30, 2016 at 11:54 AM, Sowmini Varadhan <sowmini.varad...@oracle.com> wrote: > Although TPACKET_V3 Rx has some benefits over TPACKET_V2 Rx, > *_v3 does not currently have Tx support. As a result an application > that wants the best perf for Tx and Rx (e.g. to handle > request/response transacations) ends up needing 2 sockets, > one with *_v2 for Tx and another with *_v3 for Rx. > > This patch enables TPACKET_V2 compatible Tx features in TPACKET_V3 > so that _v3 supports at least as many features as _v2.
Once we define the interface as equivalent to v2, we cannot redefine it to support v3-only features later. > Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com> > --- > Documentation/networking/packet_mmap.txt | 6 ++++-- > net/packet/af_packet.c | 23 +++++++++++++++-------- > 2 files changed, 19 insertions(+), 10 deletions(-) > > diff --git a/Documentation/networking/packet_mmap.txt > b/Documentation/networking/packet_mmap.txt > index daa015a..6425062 100644 > --- a/Documentation/networking/packet_mmap.txt > +++ b/Documentation/networking/packet_mmap.txt > @@ -565,7 +565,7 @@ where 'tpacket_version' can be TPACKET_V1 (default), > TPACKET_V2, TPACKET_V3. > (void *)hdr + TPACKET_ALIGN(sizeof(struct tpacket_hdr)) > > TPACKET_V2 --> TPACKET_V3: > - - Flexible buffer implementation: > + - Flexible buffer implementation for RX_RING: > 1. Blocks can be configured with non-static frame-size This is one of the main advantages of the v3 interface, and also relevant to Tx. The current implementation does not consult tpacket3_hdr->tp_next_offset and would preclude adding that later.
