Hi Jerin,
> -----Original Message-----
> From: Jerin Jacob <jerinjac...@gmail.com>
> Sent: Monday, March 9, 2020 3:36 PM
> To: Gavin Hu <gavin...@arm.com>
> Cc: dpdk-dev <dev@dpdk.org>; nd <n...@arm.com>; David Marchand
> <david.march...@redhat.com>; tho...@monjalon.net; jer...@marvell.com;
> Ye, Xiaolong <xiaolong...@intel.com>; Honnappa Nagarahalli
> <honnappa.nagaraha...@arm.com>; Ruifeng Wang
> <ruifeng.w...@arm.com>; Phil Yang <phil.y...@arm.com>; Joyce Kong
> <joyce.k...@arm.com>; Steve Capper <steve.cap...@arm.com>
> Subject: Re: [dpdk-dev] [PATCH v1 3/3] net/i40e: auto-vectorization to speed
> up Tx free
>
> On Sat, Mar 7, 2020 at 8:34 PM Gavin Hu <gavin...@arm.com> wrote:
> >
> > Hi Jerin,
> >
> > > -----Original Message-----
> > > From: Jerin Jacob <jerinjac...@gmail.com>
> > > Sent: Friday, March 6, 2020 3:45 PM
> > > To: Gavin Hu <gavin...@arm.com>
> > > Cc: dpdk-dev <dev@dpdk.org>; nd <n...@arm.com>; David Marchand
> > > <david.march...@redhat.com>; tho...@monjalon.net;
> > > jer...@marvell.com; Ye, Xiaolong <xiaolong...@intel.com>; Honnappa
> > > Nagarahalli <honnappa.nagaraha...@arm.com>; Ruifeng Wang
> > > <ruifeng.w...@arm.com>; Phil Yang <phil.y...@arm.com>; Joyce Kong
> > > <joyce.k...@arm.com>; Steve Capper <steve.cap...@arm.com>
> > > Subject: Re: [dpdk-dev] [PATCH v1 3/3] net/i40e: auto-vectorization to
> > > speed up Tx free
> > >
> > > On Fri, Mar 6, 2020 at 10:35 AM Gavin Hu <gavin...@arm.com> wrote:
> > > >
> > > > Tx mbuf free is a hotspot for i40e on aarch64, as there are no
> > > > inter-loop dependencies, it is safe to enable auto-vectorization
> > > > to speed up.
> > > >
> > > > This patch showed 2~3% performance lift on ThunderX2 and no
> > > degradation
> > > > on Arm N1SDP. The test case is single core RFC2544 zero-loss test.
> > > >
> > > > Signed-off-by: Gavin Hu <gavin...@arm.com>
> > > > Reviewed-by: Steve Capper <steve.cap...@arm.com>
> > > > ---
> > > > drivers/net/i40e/i40e_rxtx_vec_common.h | 5 +++++
> > > > 1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/drivers/net/i40e/i40e_rxtx_vec_common.h
> > > b/drivers/net/i40e/i40e_rxtx_vec_common.h
> > > > index 0e6ffa007..fc0fa45d4 100644
> > > > --- a/drivers/net/i40e/i40e_rxtx_vec_common.h
> > > > +++ b/drivers/net/i40e/i40e_rxtx_vec_common.h
> > > > @@ -98,6 +98,11 @@ i40e_tx_free_bufs(struct i40e_tx_queue *txq)
> > > > if (likely(m != NULL)) {
> > > > free[0] = m;
> > > > nb_free = 1;
> > > > +#if defined(__clang__)
> > > > +#pragma clang loop vectorize(assume_safety)
> > > > +#elif defined(__GNUC__)
> > > > +#pragma GCC ivdep
> > > > +#endif
> > >
> > > IMO, It is better to abstract the compiler features (above compiler
> > > feature and __restrict__) as macros in
> > > rte_common.h or so. It will help to support other compilers(ICC or
> > > Windows) and enable them to have "changes" in one place.
> >
> > How about defining RTE_LOOP_AUTO_VECTORIZATION in the
> rte_common.h?
>
> Other compiler stuff in rte_common.h are starting with __rte in small
> letter(__rte_packed, __rte_unused) etc.
> I think, a better name would be __rte_loop_auto_vectorize or so.
> No strong opinion for the name though.
>
> # Probably it is worth checking and add performance result of x86
> testing in git commit as well as it
> is common code.
Okay, I will do it.
>
>
> > #if defined(__clang__)
> > define RTE_LOOP_AUTO_VECTORIZATION \
> > #pragma clang loop vectorize(assume_safety)
> > #elif defined(__GNUC__)
> > define RTE_LOOP_AUTO_VECTORIZATION \
> > #pragma GCC ivdep
> > #else
> > define RTE_LOOP_AUTO_VECTORIZATION
> > #endif
> > If you agree, I will submit a v2. Thanks for your comments!
> > /Gavin
> > >
> > >
> > >
> > > > for (i = 1; i < n; i++) {
> > > > m = rte_pktmbuf_prefree_seg(txep[i].mbuf);
> > > > if (likely(m != NULL)) {
> > > > --
> > > > 2.17.1
> > > >
