Re: [PATCH v2 1/2] Update AVX512 support for xbzrle_encode_buffer function

[Daniel P . Berrangé]

On Fri, Aug 05, 2022 at 12:25:07PM +0800, ling xu wrote:
> This commit adds runtime check of AVX512 on running machine, and implements 
> AVX512 of
> xbzrle_encode_buffer function to accelerate xbzrle encoding speed.
> Compared with C version of xbzrle_encode_buffer function, AVX512 version
> can achieve almost 60%-70% performance improvement on unit test provided
> by qemu. In addition, we provide one more unit test called
> "test_encode_decode_random", in which dirty data are randomly located in
> 4K page, and this case can achieve almost 140% performance gain.
> 
> Signed-off-by: ling xu <ling1.xu@intel.com>
> Co-authored-by: Zhou Zhao <zhou.zhao@intel.com>
> Co-authored-by: Jun Jin <jun.i.jin@intel.com>
> ---
>  meson.build        | 211 +++++++++++++++++++++++++++++++++++++++++++++
>  meson_options.txt  |  28 ++++++
>  migration/ram.c    |  41 +++++++++
>  migration/xbzrle.c | 181 ++++++++++++++++++++++++++++++++++++++
>  migration/xbzrle.h |   4 +
>  5 files changed, 465 insertions(+)
> 
> diff --git a/meson.build b/meson.build
> index 294e9a8f32..9228df2442 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2262,6 +2262,217 @@ config_host_data.set('CONFIG_AVX512F_OPT', 
> get_option('avx512f') \
>      int main(int argc, char *argv[]) { return bar(argv[0]); }
>    '''), error_message: 'AVX512F not available').allowed())
>  
> +config_host_data.set('CONFIG_AVX512BW_OPT', get_option('avx512bw') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512BW') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512bw")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +
> +      __m512i x = *(__m512i *)a;
> +      __m512i res= _mm512_abs_epi8(x);
> +      return res[1];
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[0]); }
> +  '''), error_message: 'AVX512BW not available').allowed())
> +

This check makes sense as the later code is looking at
CONFIG_AVX512BW_OPT.


> +config_host_data.set('CONFIG_AVX512CD_OPT', get_option('avx512cd') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512CD') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512cd")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +
> +      __m512i x = *(__m512i *)a;
> +      __mmask16 k;
> +      __m512i res= _mm512_maskz_lzcnt_epi32 (k, x);
> +      return res[1];
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[0]); }
> +  '''), error_message: 'AVX512CD not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512DQ_OPT', get_option('avx512dq') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512D') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512dq")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +
> +      __mmask x = *(__mmask *)a;
> +      __mmask8 b;
> +      return _kxor_mask8(x,b);
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[0]); }
> +  '''), error_message: 'AVX512DQ not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512ER_OPT', get_option('avx512er') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512ER') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512er")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +
> +      __m512d x = *(__m512d *)a;
> +      __m512d res=_mm512_rsqrt28_pd(x);
> +      return res[1];
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[0]); }
> +  '''), error_message: 'AVX512ER not available').allowed())
> +
> +
> +config_host_data.set('CONFIG_AVX512IFMA52_OPT', get_option('avx512ifma52') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512ER') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512ifma")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +
> +      __m512i x = *(__m512i *)a;
> +      __m512i b,c;
> +      __m512i res= _mm512_madd52lo_epu64 (x, b, c);
> +      return res[1];
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[0]); }
> +  '''), error_message: 'AVX512IFMA52 not available').allowed())
> +
> +
> +config_host_data.set('CONFIG_AVX512PF_OPT', get_option('avx512pf') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512PF') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512pf")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static void bar(void *a) {
> +      char* base_addr;
> +      __mmask8 k;
> +      __m512i vindex = *(__m512i *)a;
> +      _mm512_mask_prefetch_i64scatter_pd (base_addr, k, vindex, 1, 2);
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512PF not available').allowed())
> +
> +
> +config_host_data.set('CONFIG_AVX512VPOPCNTDQ_OPT', 
> get_option('avx512vpopcntdq') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512VPOPCNTDQ') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512vpopcntdq")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +      __m512i x = *(__m512i *)a;
> +      __mmask8 k;
> +      __m512i res= _mm512_maskz_popcnt_epi64(k,a);
> +     return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512VPOPCNTDQ not available').allowed())
> +
> +
> +config_host_data.set('CONFIG_AVX5124VNNIW_OPT', get_option('avx5124vnniw') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX5124VNNIW') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx5124vnniw")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +     __m512i x = *(__m512i *)a,b,c,d,e;
> +     __m128 g;
> +     __m512i res= _mm512_4dpwssd_epi32 (x, b, c, d, e, &g);
> +     return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX5124VNNIW not available').allowed())
> +
> +
> +config_host_data.set('CONFIG_AVX512BITALG_OPT', get_option('avx512bitalg') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512BITALG') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512bitalg")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +    __m512i x  = *(__m512i *)a,b,c,d,e;
> +    __m512i res= _mm512_popcnt_epi16 (x);
> +    return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512BITALG not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512VBMI_OPT', get_option('avx512vbmi') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512VBMI') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512vbmi")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +    __m512i x  = *(__m512i *)a,b,c;
> +    __m512i res=  _mm512_permutex2var_epi8  (x, b, c);
> +    return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512VBMI not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512VBMI2_OPT', get_option('avx512vbmi2') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512VBMI') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512vbmi2")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +    __m512i x  = *(__m512i *)a,b,c;
> +    __m512i res=  _mm512_shrdv_epi64  (x, b, c);
> +    return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512VBMI2 not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512VNNI_OPT', get_option('avx512vnni') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512VNNI') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512vnni")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +    __m512i x  = *(__m512i *)a,b,c;
> +    __mmask16 k;
> +    __m512i res=  _mm512_maskz_dpwssds_epi32 (k,x, b, c);
> +    return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512VNNI not available').allowed())
> +
> +config_host_data.set('CONFIG_AVX512FP16_OPT', get_option('avx512fp16') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot 
> enable AVX512FP16') \
> +  .require(cc.links('''
> +    #pragma GCC push_options
> +    #pragma GCC target("avx512fp16")
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int bar(void *a) {
> +    __m128h x= *(__m128h *)a;
> +    __m128 res=  _mm_castph_ps (x);
> +    return res[0];
> +    }
> +    int main(int argc, char *argv[]) { bar(argv[0]); return 0;}
> +  '''), error_message: 'AVX512fp16 not available').allowed())
> +


What are all these checks for though ?  Nothing makes use of the
CONFIG_AVX512*_OPT options they're adding.  We shouldn't add them
unless they're going to be used.


With regards,
Daniel
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