Re: [PATCH v7] event/dlb2: add support for single 512B write of 4 QEs

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Jun 10, 2022 at 10:41:25AM -0500, Timothy McDaniel wrote:
> On Xeon, 512b accesses are available, so movdir64 instruction is able to
> perform 512b read and write to DLB producer port. In order for movdir64
> to be able to pull its data from store buffers (store-buffer-forwarding)
> (before actual write), data should be in single 512b write format.
> This commit add change when code is built for Xeon with 512b AVX support
> to make single 512b write of all 4 QEs instead of 4x64b writes.
> 
> Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> Acked-by: Kent Wires <kent.wires@intel.com>
> ===
> 
> Changes since V6:
> 1) Check for AVX512VL only, removing checks for other
> AVX512 flags in meson.build
> 2) rename dlb2_sve.c to dlb2_sse.c
> 
> Changes since V5:
> No code changes - just added --in-reply-to and copied Bruce
> 
> Changes since V4:
> 1) Add build-time control for avx512 support to meson.buildi, based
> on implementation found in lib/acl/meson.build
> 2) Add rte_vect_get_max_simd_bitwidth runtime check before using
> avx512 instructions
> 
> Changes since V3:
> 1) Renamed dlb2_noavx512.c to dlb2_sve.c, and fixed up meson.build
> for new file name.
> 
> Changes since V1:
> 1) Split out dlb2_event_build_hcws into two implementations, one
> that uses AVX512 instructions, and one that does not. Each implementation
> is in its own source file in order to avoid build errors if the compiler
> does not support the newer AVX512 instructions.
> 2) Update meson.build to and pull in appropriate source file based on
> whether the compiler supports AVX512VL
> 3) Check if target supports AVX512VL, and use appropriate implementation
> based on this runtime check.
> ---
>  drivers/event/dlb2/dlb2.c        | 208 +-----------------------
>  drivers/event/dlb2/dlb2_avx512.c | 267 +++++++++++++++++++++++++++++++
>  drivers/event/dlb2/dlb2_priv.h   |  10 ++
>  drivers/event/dlb2/dlb2_sse.c    | 219 +++++++++++++++++++++++++
>  drivers/event/dlb2/dlb2_sve.c    | 219 +++++++++++++++++++++++++
>  drivers/event/dlb2/meson.build   |  47 ++++++
>  6 files changed, 769 insertions(+), 201 deletions(-)
>  create mode 100644 drivers/event/dlb2/dlb2_avx512.c
>  create mode 100644 drivers/event/dlb2/dlb2_sse.c
>  create mode 100644 drivers/event/dlb2/dlb2_sve.c
> 
<snip>
> diff --git a/drivers/event/dlb2/meson.build b/drivers/event/dlb2/meson.build
> index f963589fd3..51ea5ec546 100644
> --- a/drivers/event/dlb2/meson.build
> +++ b/drivers/event/dlb2/meson.build
> @@ -19,6 +19,53 @@ sources = files(
>          'dlb2_selftest.c',
>  )
>  
> +# compile AVX512 version if:
> +# we are building 64-bit binary (checked above) AND binutils
> +# can generate proper code
> +
> +if binutils_ok
> +
> +    # compile AVX512 version if either:
> +    # a. we have AVX512VL supported in minimum instruction set
> +    #    baseline
> +    # b. it's not minimum instruction set, but supported by
> +    #    compiler
> +    #
> +    # in former case, just add avx512 C file to files list
> +    # in latter case, compile c file to static lib, using correct
> +    # compiler flags, and then have the .o file from static lib
> +    # linked into main lib.
> +
> +    # check if all required flags already enabled (variant a).
> +    dlb2_avx512_on = false
> +    if cc.get_define(f, args: machine_args) == '__AVX512VL__'
> +        dlb2_avx512_on = true
> +    endif
> +
> +    if dlb2_avx512_on == true
> +
> +        sources += files('dlb2_avx512.c')
> +        cflags += '-DCC_AVX512_SUPPORT'
> +
> +    elif cc.has_multi_arguments('-mavx512f', '-mavx512vl',
> +                                '-mavx512cd', '-mavx512bw')
> +
> +        cflags += '-DCC_AVX512_SUPPORT'
> +        avx512_tmplib = static_library('avx512_tmp',
> +                               'dlb2_avx512.c',
> +			       dependencies: [static_rte_eal,
> +			                      static_rte_eventdev],

Minor nit - incorrect whitespace

> +                               c_args: cflags +
> +                                       ['-mavx512f', '-mavx512vl',
> +                                        '-mavx512cd', '-mavx512bw'])
> +        objs += avx512_tmplib.extract_objects('dlb2_avx512.c')
> +    else
> +        sources += files('dlb2_sse.c')
> +    endif
> +else
> +        sources += files('dlb2_sse.c')
> +endif
> +
>  headers = files('rte_pmd_dlb2.h')
>  
>  deps += ['mbuf', 'mempool', 'ring', 'pci', 'bus_pci']

These meson.build file changes look ok to me now.

/Bruce