Hi Phil,
>
> For SA outbound packets, rte_atomic64_add_return is used to generate
> SQN atomically. This introduced an unnecessary full barrier by calling
> the '__sync' builtin implemented rte_atomic_XX API on aarch64. This
> patch optimized it with c11 atomic and eliminated the expensive barrier
> for aarch64.
>
> Signed-off-by: Phil Yang <phil.y...@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
> Reviewed-by: Gavin Hu <gavin...@arm.com>
> ---
> lib/librte_ipsec/ipsec_sqn.h | 3 ++-
> lib/librte_ipsec/sa.h | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_ipsec/ipsec_sqn.h b/lib/librte_ipsec/ipsec_sqn.h
> index 0c2f76a..e884af7 100644
> --- a/lib/librte_ipsec/ipsec_sqn.h
> +++ b/lib/librte_ipsec/ipsec_sqn.h
> @@ -128,7 +128,8 @@ esn_outb_update_sqn(struct rte_ipsec_sa *sa, uint32_t
> *num)
>
> n = *num;
> if (SQN_ATOMIC(sa))
> - sqn = (uint64_t)rte_atomic64_add_return(&sa->sqn.outb.atom, n);
> + sqn = __atomic_add_fetch(&sa->sqn.outb.atom, n,
> + __ATOMIC_RELAXED);
One generic thing to note:
clang for i686 in some cases will generate a proper function call for
64-bit __atomic builtins (gcc seems to always generate cmpxchng8b for such
cases).
Does anyone consider it as a potential problem?
It probably not a big deal, but would like to know broader opinion.
> else {
> sqn = sa->sqn.outb.raw + n;
> sa->sqn.outb.raw = sqn;
> diff --git a/lib/librte_ipsec/sa.h b/lib/librte_ipsec/sa.h
> index d22451b..cab9a2e 100644
> --- a/lib/librte_ipsec/sa.h
> +++ b/lib/librte_ipsec/sa.h
> @@ -120,7 +120,7 @@ struct rte_ipsec_sa {
> */
> union {
> union {
> - rte_atomic64_t atom;
> + uint64_t atom;
> uint64_t raw;
> } outb;
If we don't need rte_atomic64 here anymore,
then I think we can collapse the union to just:
uint64_t outb;
> struct {
> --
> 2.7.4
