Re: [dpdk-dev] [PATCH v2] ipsec: optimize with c11 atomic for sa outbound sqn update

[Phil Yang <Phil.Yang@arm.com>]

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Friday, April 24, 2020 2:11 AM
> To: Phil Yang <Phil.Yang@arm.com>; dev@dpdk.org
> Cc: thomas@monjalon.net; Iremonger, Bernard
> <bernard.iremonger@intel.com>; Medvedkin, Vladimir
> <vladimir.medvedkin@intel.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; Gavin Hu <Gavin.Hu@arm.com>;
> Ruifeng Wang <Ruifeng.Wang@arm.com>; nd <nd@arm.com>
> Subject: RE: [PATCH v2] ipsec: optimize with c11 atomic for sa outbound sqn
> update
> 
> >
> > 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.yang@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> > ---
> > v2:
> > split from the "generic rte atomic APIs deprecate proposal" patchset.
> >
> >
> >  lib/librte_ipsec/ipsec_sqn.h | 3 ++-
> >  lib/librte_ipsec/meson.build | 5 +++++
> >  lib/librte_ipsec/sa.h        | 2 +-
> >  3 files changed, 8 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);
> >  	else {
> >  		sqn = sa->sqn.outb.raw + n;
> >  		sa->sqn.outb.raw = sqn;
> > diff --git a/lib/librte_ipsec/meson.build b/lib/librte_ipsec/meson.build
> > index fc69970..9335f28 100644
> > --- a/lib/librte_ipsec/meson.build
> > +++ b/lib/librte_ipsec/meson.build
> > @@ -6,3 +6,8 @@ sources = files('esp_inb.c', 'esp_outb.c', 'sa.c', 'ses.c',
> 'ipsec_sad.c')
> >  headers = files('rte_ipsec.h', 'rte_ipsec_group.h', 'rte_ipsec_sa.h',
> 'rte_ipsec_sad.h')
> >
> >  deps += ['mbuf', 'net', 'cryptodev', 'security', 'hash']
> > +
> > +# for clang 32-bit compiles we need libatomic for 64-bit atomic ops
> > +if cc.get_id() == 'clang' and dpdk_conf.get('RTE_ARCH_64') == false
> > +    ext_deps += cc.find_library('atomic')
> > +endif
> > 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;
> >  		struct {
> 
> Seems  you missed my comments for previous version, so I put here:
> 
> If we don't need rte_atomic64 here anymore,
> then I think we can collapse the union to just:
> uint64_t outb;
My bad, I missed this comment.
Updated in v3.  Please review it.

Thanks,
Phil

> 
> Konstantin