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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi David,

> > > 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

LGTM, thanks.
Konstantin