OVS and some other applications have been hacking into DPDK internals to fake EAL threads and avoid performance penalty of only having non-EAL threads.
This series proposes to add a new type of lcores and maps those threads to such lcores. non-EAL threads won't run the DPDK eal mainloop. As a consequence, part of the EAL threads API cannot work. Having new lcores appearing during the process lifetime is not expected by some DPDK components. This is addressed by introducing init/uninit callacks invoked when hotplugging of such lcore. There is still some work/discussion: - refuse new lcore role in incompatible EAL threads API (or document it only as those API were already incompatible?), - think about deprecation notices for existing RTE_FOREACH_LCORE macros and consorts, it is probably worth discussing on how to iterate over lcores, For the interested parties, I have a patch  against dpdk-latest OVS branch that makes use of this series. 1: https://patchwork.ozlabs.org/project/openvswitch/patch/20200626123017.28555-1-david.march...@redhat.com/ Changes since v3: - added init failure when trying to use in conjunction with multiprocess, - addressed Andrew comments, Changes since v2: - fixed windows build error due to missing trace stub, - fixed bug when rolling back on lcore register, Changes since v1: - rebased on master (conflicts on merged Windows series), - separated lcore role code cleanup in a patch, - tried to use a single naming, so kept non-EAL threads as the main notion. non-EAL threads are then distinguished between registered and unregistered non-EAL threads, - added unit tests (still missing some coverage, marked with a FIXME), - reworked callbacks call under a common rwlock lock which protects lcores allocations and callbacks registration, - introduced lcore iterators and converted the bucket mempool driver, -- David Marchand David Marchand (9): eal: relocate per thread symbols to common eal: fix multiple definition of per lcore thread id eal: introduce thread init helper eal: introduce thread uninit helper eal: move lcore role code eal: register non-EAL threads as lcores eal: add lcore init callbacks eal: add lcore iterators mempool/bucket: handle non-EAL lcores MAINTAINERS | 1 + app/test/Makefile | 1 + app/test/autotest_data.py | 6 + app/test/meson.build | 2 + app/test/test_lcores.c | 372 ++++++++++++++++++ doc/guides/howto/debug_troubleshoot.rst | 5 +- .../prog_guide/env_abstraction_layer.rst | 22 +- doc/guides/prog_guide/mempool_lib.rst | 2 +- drivers/mempool/bucket/rte_mempool_bucket.c | 130 +++--- lib/librte_eal/common/eal_common_lcore.c | 246 +++++++++++- lib/librte_eal/common/eal_common_mcfg.c | 36 ++ lib/librte_eal/common/eal_common_thread.c | 126 ++++-- lib/librte_eal/common/eal_common_trace.c | 51 ++- lib/librte_eal/common/eal_memcfg.h | 10 + lib/librte_eal/common/eal_private.h | 19 + lib/librte_eal/common/eal_thread.h | 26 +- lib/librte_eal/common/eal_trace.h | 2 +- lib/librte_eal/freebsd/eal.c | 20 +- lib/librte_eal/freebsd/eal_thread.c | 38 +- lib/librte_eal/include/rte_eal.h | 12 +- lib/librte_eal/include/rte_lcore.h | 174 +++++++- lib/librte_eal/include/rte_trace_point.h | 9 + lib/librte_eal/linux/eal.c | 21 +- lib/librte_eal/linux/eal_thread.c | 38 +- lib/librte_eal/rte_eal_version.map | 16 + lib/librte_eal/windows/eal.c | 8 +- lib/librte_eal/windows/eal_thread.c | 14 +- lib/librte_mempool/rte_mempool.h | 11 +- 28 files changed, 1179 insertions(+), 239 deletions(-) create mode 100644 app/test/test_lcores.c -- 2.23.0