lib/dpif-netdev-lookup.c

   1 /*
   2  * Copyright (c) 2020 Intel Corporation.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include <errno.h>
  19 #include "dpif-netdev-lookup.h"
  20
  21 #include "openvswitch/vlog.h"
  22
  23 VLOG_DEFINE_THIS_MODULE(dpif_netdev_lookup);
  24
  25 /* Actual list of implementations goes here */
  26 static struct dpcls_subtable_lookup_info_t subtable_lookups[] = {
  27     /* The autovalidator implementation will not be used by default, it must
  28      * be enabled at compile time to be the default lookup implementation. The
  29      * user may enable it at runtime using the normal "prio-set" command if
  30      * desired. The compile time default switch is here to enable all unit
  31      * tests to transparently run with the autovalidator.
  32      */
  33 #ifdef DPCLS_AUTOVALIDATOR_DEFAULT
  34     { .prio = 255,
  35 #else
  36     { .prio = 0,
  37 #endif
  38       .probe = dpcls_subtable_autovalidator_probe,
  39       .name = "autovalidator", },
  40
  41     /* The default scalar C code implementation. */
  42     { .prio = 1,
  43       .probe = dpcls_subtable_generic_probe,
  44       .name = "generic", },
  45
  46 #if (__x86_64__ && HAVE_AVX512F && HAVE_LD_AVX512_GOOD && __SSE4_2__)
  47     /* Only available on x86_64 bit builds with SSE 4.2 used for OVS core. */
  48     { .prio = 0,
  49       .probe = dpcls_subtable_avx512_gather_probe,
  50       .name = "avx512_gather", },
  51 #else
  52     /* Disabling AVX512 at compile time, as compile time requirements not met.
  53      * This could be due to a number of reasons:
  54      *  1) core OVS is not compiled with SSE4.2 instruction set.
  55      *     The SSE42 instructions are required to use CRC32 ISA for high-
  56      *     performance hashing. Consider ./configure of OVS with -msse42 (or
  57      *     newer) to enable CRC32 hashing and higher performance.
  58      *  2) The assembler in binutils versions 2.30 and 2.31 has bugs in AVX512
  59      *     assembly. Compile time probes check for this assembler issue, and
  60      *     disable the HAVE_LD_AVX512_GOOD check if an issue is detected.
  61      *     Please upgrade binutils, or backport this binutils fix commit:
  62      *     2069ccaf8dc28ea699bd901fdd35d90613e4402a
  63      */
  64 #endif
  65 };
  66
  67 int32_t
  68 dpcls_subtable_lookup_info_get(struct dpcls_subtable_lookup_info_t **out_ptr)
  69 {
  70     if (out_ptr == NULL) {
  71         return -1;
  72     }
  73
  74     *out_ptr = subtable_lookups;
  75     return ARRAY_SIZE(subtable_lookups);
  76 }
  77
  78 /* sets the priority of the lookup function with "name". */
  79 int32_t
  80 dpcls_subtable_set_prio(const char *name, uint8_t priority)
  81 {
  82     for (int i = 0; i < ARRAY_SIZE(subtable_lookups); i++) {
  83         if (strcmp(name, subtable_lookups[i].name) == 0) {
  84                 subtable_lookups[i].prio = priority;
  85                 VLOG_INFO("Subtable function '%s' set priority to %d\n",
  86                          name, priority);
  87                 return 0;
  88         }
  89     }
  90     VLOG_WARN("Subtable function '%s' not found, failed to set priority\n",
  91               name);
  92     return -EINVAL;
  93 }
  94
  95 dpcls_subtable_lookup_func
  96 dpcls_subtable_get_best_impl(uint32_t u0_bit_count, uint32_t u1_bit_count)
  97 {
  98     /* Iter over each subtable impl, and get highest priority one. */
  99     int32_t prio = -1;
 100     const char *name = NULL;
 101     dpcls_subtable_lookup_func best_func = NULL;
 102
 103     for (int i = 0; i < ARRAY_SIZE(subtable_lookups); i++) {
 104         int32_t probed_prio = subtable_lookups[i].prio;
 105         if (probed_prio > prio) {
 106             dpcls_subtable_lookup_func probed_func;
 107             probed_func = subtable_lookups[i].probe(u0_bit_count,
 108                                     u1_bit_count);
 109             if (probed_func) {
 110                 best_func = probed_func;
 111                 prio = probed_prio;
 112                 name = subtable_lookups[i].name;
 113             }
 114         }
 115     }
 116
 117     VLOG_DBG("Subtable lookup function '%s' with units (%d,%d), priority %d\n",
 118              name, u0_bit_count, u1_bit_count, prio);
 119
 120     /* Programming error - we must always return a valid func ptr. */
 121     ovs_assert(best_func != NULL);
 122
 123     return best_func;
 124 }