| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #include <grpc/support/port_platform.h> |
| |
| #ifdef GPR_CPU_POSIX |
| |
| #include <errno.h> |
| #include <unistd.h> |
| #include <string.h> |
| |
| #include <grpc/support/log.h> |
| #include <grpc/support/sync.h> |
| |
| static __thread char magic_thread_local; |
| |
| static int ncpus = 0; |
| |
| static void init_ncpus() { |
| ncpus = sysconf(_SC_NPROCESSORS_ONLN); |
| if (ncpus < 1) { |
| gpr_log(GPR_ERROR, "Cannot determine number of CPUs: assuming 1"); |
| ncpus = 1; |
| } |
| } |
| |
| unsigned gpr_cpu_num_cores(void) { |
| static gpr_once once = GPR_ONCE_INIT; |
| gpr_once_init(&once, init_ncpus); |
| return ncpus; |
| } |
| |
| /* This is a cheap, but good enough, pointer hash for sharding things: */ |
| static size_t shard_ptr(const void *info) { |
| size_t x = (size_t)info; |
| return ((x >> 4) ^ (x >> 9) ^ (x >> 14)) % gpr_cpu_num_cores(); |
| } |
| |
| unsigned gpr_cpu_current_cpu(void) { |
| /* NOTE: there's no way I know to return the actual cpu index portably... |
| most code that's using this is using it to shard across work queues though, |
| so here we use thread identity instead to achieve a similar though not |
| identical effect */ |
| return shard_ptr(&magic_thread_local); |
| } |
| |
| #endif /* GPR_CPU_LINUX */ |