Re: [dpdk-dev] [PATCH v4 1/2] net: add run-time architecture specific CRC selection

["Coyle, David" <david.coyle@intel.com>]

Hi Konstantin, thanks for your review

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Wednesday, October 7, 2020 3:59 PM

<snip>

> 
> >
> > This patch adds support for run-time selection of the optimal
> > architecture-specific CRC path, based on the supported instruction
> > set(s) of the CPU.
> >
> > The compiler option checks have been moved from the C files to the
> > meson script. The rte_cpu_get_flag_enabled function is called
> > automatically by the library at process initialization time to
> > determine which instructions the CPU supports, with the most optimal
> > supported CRC path ultimately selected.
> >
> > Signed-off-by: Mairtin o Loingsigh <mairtin.oloingsigh@intel.com>
> > Signed-off-by: David Coyle <david.coyle@intel.com>
> 
> LGTM, just one nit see below.
> With that:
> Series acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> 
> > ---
> >  doc/guides/rel_notes/release_20_11.rst            |  4 ++
> >  lib/librte_net/meson.build                        | 34 +++++++++++-
> >  lib/librte_net/net_crc.h                          | 34 ++++++++++++
> >  lib/librte_net/{net_crc_neon.h => net_crc_neon.c} | 26 +++------
> >  lib/librte_net/{net_crc_sse.h => net_crc_sse.c}   | 34 ++++--------
> >  lib/librte_net/rte_net_crc.c                      | 67 ++++++++++++++---------
> >  6 files changed, 131 insertions(+), 68 deletions(-)  create mode
> > 100644 lib/librte_net/net_crc.h  rename lib/librte_net/{net_crc_neon.h
> > => net_crc_neon.c} (95%)  rename lib/librte_net/{net_crc_sse.h =>
> > net_crc_sse.c} (94%)
> >
> >

<snip>

> > +#ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT static uint8_t
> > +sse42_pclmulqdq_cpu_supported(void)
> > +{
> > +	return rte_cpu_get_flag_enabled(RTE_CPUFLAG_PCLMULQDQ);
> > +}
> 
> As a nit, I think it would be better to hide #fidef inside the function, and
> return an 0 when define is not set.
> Something like:
> 
> static int
> sse42_pclmulqdq_cpu_supported(void)
> {
> #ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT
> 	return rte_cpu_get_flag_enabled(RTE_CPUFLAG_PCLMULQDQ);
> #else
> 	return 0;
> }
> 
> Same for other cpu_supported functions.
> And then you can remove these ifdefs in set_alg and other palces, i.e.:
> 
> void
> rte_net_crc_set_alg(enum rte_net_crc_alg alg) {
>         switch (alg) {
> #ifdef RTE_ARCH_X86_64
>         case RTE_NET_CRC_AVX512:
>                 if (avx512_vpclmulqdq_cpu_supported()) {
>                         handlers = handlers_avx512;
>                         break;
>                 }
>                 /* fall-through */
>         case RTE_NET_CRC_SSE42:
>                 if (sse42_pclmulqdq_cpu_supported()) {
>                         handlers = handlers_sse42;
>                         break;
>                 }
> #endif
> ...
> 
> Same for rte_net_crc_init()

[DC] I have reworked the ifdefs in this file based on your comments here and off-list discussions.
These are available now in the v5.

All ifdef's have been removed out the API function definitions and moved down into 'helper' type
functions - looks much cleaner now.

Your Ack has been carried through too to v5 as you mentioned

> 
> > +#endif
> > +
> > +#ifdef CC_ARM64_NEON_PMULL_SUPPORT
> > +static uint8_t
> > +neon_pmull_cpu_supported(void)
> > +{
> > +	return rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL);
> > +}
> > +#endif
> > +
> >  void
> >  rte_net_crc_set_alg(enum rte_net_crc_alg alg)  {
> >  	switch (alg) {
> > -#ifdef X86_64_SSE42_PCLMULQDQ
> > +#ifdef RTE_ARCH_X86_64
> >  	case RTE_NET_CRC_SSE42:
> > -		handlers = handlers_sse42;
> > -		break;
> > -#elif defined ARM64_NEON_PMULL
> > -		/* fall-through */
> > +#ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT
> > +		if (sse42_pclmulqdq_cpu_supported()) {
> > +			handlers = handlers_sse42;
> > +			break;
> > +		}
> > +#endif
> > +#endif /* RTE_ARCH_X86_64 */
> > +#ifdef RTE_ARCH_ARM64
> >  	case RTE_NET_CRC_NEON:
> > -		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL)) {
> > +#ifdef CC_ARM64_NEON_PMULL_SUPPORT
> > +		if (neon_pmull_cpu_supported()) {
> >  			handlers = handlers_neon;
> >  			break;
> >  		}
> >  #endif
> > +#endif /* RTE_ARCH_ARM64 */
> >  		/* fall-through */
> >  	case RTE_NET_CRC_SCALAR:
> >  		/* fall-through */
> > @@ -188,11 +200,14 @@ RTE_INIT(rte_net_crc_init)
> >
> >  	rte_net_crc_scalar_init();
> >
> > -#ifdef X86_64_SSE42_PCLMULQDQ
> > -	alg = RTE_NET_CRC_SSE42;
> > -	rte_net_crc_sse42_init();
> > -#elif defined ARM64_NEON_PMULL
> > -	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_PMULL)) {
> > +#ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT
> > +	if (sse42_pclmulqdq_cpu_supported()) {
> > +		alg = RTE_NET_CRC_SSE42;
> > +		rte_net_crc_sse42_init();
> > +	}
> > +#endif
> > +#ifdef CC_ARM64_NEON_PMULL_SUPPORT
> > +	if (neon_pmull_cpu_supported()) {
> >  		alg = RTE_NET_CRC_NEON;
> >  		rte_net_crc_neon_init();
> >  	}
> > --
> > 2.12.3