| Message ID | 20190724170018.96659-1-sdf@google.com |
|---|---|
| Headers | show |
| Series | bpf/flow_dissector: support input flags | expand |
On Wed, Jul 24, 2019 at 1:11 PM Stanislav Fomichev <sdf@google.com> wrote: > > C flow dissector supports input flags that tell it to customize parsing > by either stopping early or trying to parse as deep as possible. > BPF flow dissector always parses as deep as possible which is sub-optimal. > Pass input flags to the BPF flow dissector as well so it can make the same > decisions. > > Series outline: > * remove unused FLOW_DISSECTOR_F_STOP_AT_L3 flag > * export FLOW_DISSECTOR_F_XXX flags as uapi and pass them to BPF > flow dissector > * add documentation for the export flags > * support input flags in BPF_PROG_TEST_RUN via ctx_{in,out} > * sync uapi to tools > * support FLOW_DISSECTOR_F_PARSE_1ST_FRAG in selftest > * support FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL in kernel and selftest > * support FLOW_DISSECTOR_F_STOP_AT_ENCAP in selftest > > Pros: > * makes BPF flow dissector faster by avoiding burning extra cycles > * existing BPF progs continue to work by ignoring the flags and always > parsing as deep as possible > > Cons: > * new UAPI which we need to support (OTOH, if we need to deprecate some > flags, we can just stop setting them upon calling BPF programs) > > Some numbers (with .repeat = 4000000 in test_flow_dissector): > test_flow_dissector:PASS:ipv4-frag 35 nsec > test_flow_dissector:PASS:ipv4-frag 35 nsec > test_flow_dissector:PASS:ipv4-no-frag 32 nsec > test_flow_dissector:PASS:ipv4-no-frag 32 nsec > > test_flow_dissector:PASS:ipv6-frag 39 nsec > test_flow_dissector:PASS:ipv6-frag 39 nsec > test_flow_dissector:PASS:ipv6-no-frag 36 nsec > test_flow_dissector:PASS:ipv6-no-frag 36 nsec > > test_flow_dissector:PASS:ipv6-flow-label 36 nsec > test_flow_dissector:PASS:ipv6-flow-label 36 nsec > test_flow_dissector:PASS:ipv6-no-flow-label 33 nsec > test_flow_dissector:PASS:ipv6-no-flow-label 33 nsec > > test_flow_dissector:PASS:ipip-encap 38 nsec > test_flow_dissector:PASS:ipip-encap 38 nsec > test_flow_dissector:PASS:ipip-no-encap 32 nsec > test_flow_dissector:PASS:ipip-no-encap 32 nsec > > The improvement is around 10%, but it's in a tight cache-hot > BPF_PROG_TEST_RUN loop. > > Cc: Willem de Bruijn <willemb@google.com> > Cc: Petar Penkov <ppenkov@google.com> This looks great to me. Thanks, Stan! Acked-by: Willem de Bruijn <willemb@google.com>
C flow dissector supports input flags that tell it to customize parsing by either stopping early or trying to parse as deep as possible. BPF flow dissector always parses as deep as possible which is sub-optimal. Pass input flags to the BPF flow dissector as well so it can make the same decisions. Series outline: * remove unused FLOW_DISSECTOR_F_STOP_AT_L3 flag * export FLOW_DISSECTOR_F_XXX flags as uapi and pass them to BPF flow dissector * add documentation for the export flags * support input flags in BPF_PROG_TEST_RUN via ctx_{in,out} * sync uapi to tools * support FLOW_DISSECTOR_F_PARSE_1ST_FRAG in selftest * support FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL in kernel and selftest * support FLOW_DISSECTOR_F_STOP_AT_ENCAP in selftest Pros: * makes BPF flow dissector faster by avoiding burning extra cycles * existing BPF progs continue to work by ignoring the flags and always parsing as deep as possible Cons: * new UAPI which we need to support (OTOH, if we need to deprecate some flags, we can just stop setting them upon calling BPF programs) Some numbers (with .repeat = 4000000 in test_flow_dissector): test_flow_dissector:PASS:ipv4-frag 35 nsec test_flow_dissector:PASS:ipv4-frag 35 nsec test_flow_dissector:PASS:ipv4-no-frag 32 nsec test_flow_dissector:PASS:ipv4-no-frag 32 nsec test_flow_dissector:PASS:ipv6-frag 39 nsec test_flow_dissector:PASS:ipv6-frag 39 nsec test_flow_dissector:PASS:ipv6-no-frag 36 nsec test_flow_dissector:PASS:ipv6-no-frag 36 nsec test_flow_dissector:PASS:ipv6-flow-label 36 nsec test_flow_dissector:PASS:ipv6-flow-label 36 nsec test_flow_dissector:PASS:ipv6-no-flow-label 33 nsec test_flow_dissector:PASS:ipv6-no-flow-label 33 nsec test_flow_dissector:PASS:ipip-encap 38 nsec test_flow_dissector:PASS:ipip-encap 38 nsec test_flow_dissector:PASS:ipip-no-encap 32 nsec test_flow_dissector:PASS:ipip-no-encap 32 nsec The improvement is around 10%, but it's in a tight cache-hot BPF_PROG_TEST_RUN loop. Cc: Willem de Bruijn <willemb@google.com> Cc: Petar Penkov <ppenkov@google.com> Stanislav Fomichev (7): bpf/flow_dissector: pass input flags to BPF flow dissector program bpf/flow_dissector: document flags bpf/flow_dissector: support flags in BPF_PROG_TEST_RUN tools/bpf: sync bpf_flow_keys flags sefltests/bpf: support FLOW_DISSECTOR_F_PARSE_1ST_FRAG bpf/flow_dissector: support ipv6 flow_label and FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL selftests/bpf: support FLOW_DISSECTOR_F_STOP_AT_ENCAP Documentation/bpf/prog_flow_dissector.rst | 18 ++ include/linux/skbuff.h | 2 +- include/net/flow_dissector.h | 4 - include/uapi/linux/bpf.h | 6 + net/bpf/test_run.c | 39 ++- net/core/flow_dissector.c | 14 +- tools/include/uapi/linux/bpf.h | 6 + .../selftests/bpf/prog_tests/flow_dissector.c | 235 ++++++++++++++++++ tools/testing/selftests/bpf/progs/bpf_flow.c | 46 +++- 9 files changed, 353 insertions(+), 17 deletions(-)