module/zcommon/zfs_fletcher_superscalar.c

   1 /*
   2  * Implement fast Fletcher4 using superscalar pipelines.
   3  *
   4  * Use regular C code to compute
   5  * Fletcher4 in two incremental 64-bit parallel accumulator streams,
   6  * and then combine the streams to form the final four checksum words.
   7  * This implementation is a derivative of the AVX SIMD implementation by
   8  * James Guilford and Jinshan Xiong from Intel (see zfs_fletcher_intel.c).
   9  *
  10  * Copyright (C) 2016 Romain Dolbeau.
  11  *
  12  * Authors:
  13  *      Romain Dolbeau <romain.dolbeau@atos.net>
  14  *
  15  * This software is available to you under a choice of one of two
  16  * licenses.  You may choose to be licensed under the terms of the GNU
  17  * General Public License (GPL) Version 2, available from the file
  18  * COPYING in the main directory of this source tree, or the
  19  * OpenIB.org BSD license below:
  20  *
  21  *     Redistribution and use in source and binary forms, with or
  22  *     without modification, are permitted provided that the following
  23  *     conditions are met:
  24  *
  25  *      - Redistributions of source code must retain the above
  26  *        copyright notice, this list of conditions and the following
  27  *        disclaimer.
  28  *
  29  *      - Redistributions in binary form must reproduce the above
  30  *        copyright notice, this list of conditions and the following
  31  *        disclaimer in the documentation and/or other materials
  32  *        provided with the distribution.
  33  *
  34  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  35  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  36  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  37  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  38  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  39  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  40  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  41  * SOFTWARE.
  42  */
  43
  44 #include <sys/byteorder.h>
  45 #include <sys/spa_checksum.h>
  46 #include <sys/strings.h>
  47 #include <zfs_fletcher.h>
  48
  49 static void
  50 fletcher_4_superscalar_init(fletcher_4_ctx_t *ctx)
  51 {
  52         bzero(ctx->superscalar, 4 * sizeof (zfs_fletcher_superscalar_t));
  53 }
  54
  55 static void
  56 fletcher_4_superscalar_fini(fletcher_4_ctx_t *ctx, zio_cksum_t *zcp)
  57 {
  58         uint64_t A, B, C, D;
  59         A = ctx->superscalar[0].v[0] + ctx->superscalar[0].v[1];
  60         B = 2 * ctx->superscalar[1].v[0] + 2 * ctx->superscalar[1].v[1] -
  61             ctx->superscalar[0].v[1];
  62         C = 4 * ctx->superscalar[2].v[0] - ctx->superscalar[1].v[0] +
  63             4 * ctx->superscalar[2].v[1] - 3 * ctx->superscalar[1].v[1];
  64         D = 8 * ctx->superscalar[3].v[0] - 4 * ctx->superscalar[2].v[0] +
  65             8 * ctx->superscalar[3].v[1] - 8 * ctx->superscalar[2].v[1] +
  66             ctx->superscalar[1].v[1];
  67         ZIO_SET_CHECKSUM(zcp, A, B, C, D);
  68 }
  69
  70 static void
  71 fletcher_4_superscalar_native(fletcher_4_ctx_t *ctx,
  72     const void *buf, uint64_t size)
  73 {
  74         const uint32_t *ip = buf;
  75         const uint32_t *ipend = ip + (size / sizeof (uint32_t));
  76         uint64_t a, b, c, d;
  77         uint64_t a2, b2, c2, d2;
  78
  79         a = ctx->superscalar[0].v[0];
  80         b = ctx->superscalar[1].v[0];
  81         c = ctx->superscalar[2].v[0];
  82         d = ctx->superscalar[3].v[0];
  83         a2 = ctx->superscalar[0].v[1];
  84         b2 = ctx->superscalar[1].v[1];
  85         c2 = ctx->superscalar[2].v[1];
  86         d2 = ctx->superscalar[3].v[1];
  87
  88         for (; ip < ipend; ip += 2) {
  89                 a += ip[0];
  90                 a2 += ip[1];
  91                 b += a;
  92                 b2 += a2;
  93                 c += b;
  94                 c2 += b2;
  95                 d += c;
  96                 d2 += c2;
  97         }
  98
  99         ctx->superscalar[0].v[0] = a;
 100         ctx->superscalar[1].v[0] = b;
 101         ctx->superscalar[2].v[0] = c;
 102         ctx->superscalar[3].v[0] = d;
 103         ctx->superscalar[0].v[1] = a2;
 104         ctx->superscalar[1].v[1] = b2;
 105         ctx->superscalar[2].v[1] = c2;
 106         ctx->superscalar[3].v[1] = d2;
 107 }
 108
 109 static void
 110 fletcher_4_superscalar_byteswap(fletcher_4_ctx_t *ctx,
 111     const void *buf, uint64_t size)
 112 {
 113         const uint32_t *ip = buf;
 114         const uint32_t *ipend = ip + (size / sizeof (uint32_t));
 115         uint64_t a, b, c, d;
 116         uint64_t a2, b2, c2, d2;
 117
 118         a = ctx->superscalar[0].v[0];
 119         b = ctx->superscalar[1].v[0];
 120         c = ctx->superscalar[2].v[0];
 121         d = ctx->superscalar[3].v[0];
 122         a2 = ctx->superscalar[0].v[1];
 123         b2 = ctx->superscalar[1].v[1];
 124         c2 = ctx->superscalar[2].v[1];
 125         d2 = ctx->superscalar[3].v[1];
 126
 127         for (; ip < ipend; ip += 2) {
 128                 a += BSWAP_32(ip[0]);
 129                 a2 += BSWAP_32(ip[1]);
 130                 b += a;
 131                 b2 += a2;
 132                 c += b;
 133                 c2 += b2;
 134                 d += c;
 135                 d2 += c2;
 136         }
 137
 138         ctx->superscalar[0].v[0] = a;
 139         ctx->superscalar[1].v[0] = b;
 140         ctx->superscalar[2].v[0] = c;
 141         ctx->superscalar[3].v[0] = d;
 142         ctx->superscalar[0].v[1] = a2;
 143         ctx->superscalar[1].v[1] = b2;
 144         ctx->superscalar[2].v[1] = c2;
 145         ctx->superscalar[3].v[1] = d2;
 146 }
 147
 148 static boolean_t fletcher_4_superscalar_valid(void)
 149 {
 150         return (B_TRUE);
 151 }
 152
 153 const fletcher_4_ops_t fletcher_4_superscalar_ops = {
 154         .init_native = fletcher_4_superscalar_init,
 155         .compute_native = fletcher_4_superscalar_native,
 156         .fini_native = fletcher_4_superscalar_fini,
 157         .init_byteswap = fletcher_4_superscalar_init,
 158         .compute_byteswap = fletcher_4_superscalar_byteswap,
 159         .fini_byteswap = fletcher_4_superscalar_fini,
 160         .valid = fletcher_4_superscalar_valid,
 161         .name = "superscalar"
 162 };