Re: [dpdk-dev] [PATCH v3 0/4] Use correct memory ordering in eal functions

[David Marchand <david.marchand@redhat.com>]

On Mon, Oct 25, 2021 at 6:53 AM Honnappa Nagarahalli
<honnappa.nagarahalli@arm.com> wrote:
>
> v3:
> a) Added Fixes, Cc:stable#dpdk.org in 1/6
> b) Merged 3/6 & 4/6 and moved after the first commit in the series
> c) Merged 2/6 & 5/6 as they need to be in a single commit
> d) Removed use of volatile in 6/6 (Konstantin)
>
> rte_eal_remote_launch and rte_eal_wait_lcore need to provide
> correct memory ordering to address the data communication from
> main core to worker core.
>
> There are 2 use cases:
> 1) All the store operations (meant for worker) by main core
> should be visible to worker core before the worker core runs the
> assigned function
>
> 2) All the store operations by the worker core should be visible
> to the main core after rte_eal_wait_lcore returns.
>
> For the data that needs to be communicated to the worker after
> the rte_eal_remote_launch returns, load-acquire and store-release
> semantics should be used.
>
> For the main to worker communication, the pointer to function
> to execute is used as the guard variable. Hence, resetting of
> the function pointer is important.
>
> For the worker to main communication, the existing code uses the
> lcore state as the guard variable. However, it looks like
> the FINISHED state is not really required. Hence the FINISHED state
> is removed before using the state as the guard variable.
>
> Honnappa Nagarahalli (4):
>   eal: reset lcore function pointer and argument
>   eal: lcore state FINISHED is not required
>   eal: ensure correct memory ordering
>   test/ring: use relaxed barriers for ring stress test
>
>  app/test/test_ring_stress_impl.h              | 18 +++----
>  drivers/event/dpaa2/dpaa2_eventdev_selftest.c |  2 +-
>  drivers/event/octeontx/ssovf_evdev_selftest.c |  2 +-
>  drivers/event/sw/sw_evdev_selftest.c          |  4 +-
>  examples/l2fwd-keepalive/main.c               |  3 +-
>  lib/eal/common/eal_common_launch.c            | 13 ++---
>  lib/eal/freebsd/eal_thread.c                  | 45 +++++++++++++----
>  lib/eal/include/rte_launch.h                  | 21 ++++----
>  lib/eal/include/rte_service.h                 |  4 +-
>  lib/eal/linux/eal_thread.c                    | 48 +++++++++++++------
>  lib/eal/windows/eal_thread.c                  | 48 +++++++++++++------
>  11 files changed, 132 insertions(+), 76 deletions(-)

Tweaked commit titles, removed deprecation notice and updated release
notes in patch 2.
Series applied, thanks.


-- 
David Marchand