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Diffstat (limited to 'src/core/lib/support/cpu_posix.c')
-rw-r--r-- | src/core/lib/support/cpu_posix.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/src/core/lib/support/cpu_posix.c b/src/core/lib/support/cpu_posix.c new file mode 100644 index 0000000000..e508ddd8ca --- /dev/null +++ b/src/core/lib/support/cpu_posix.c @@ -0,0 +1,77 @@ +/* + * + * Copyright 2015-2016, 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 <string.h> +#include <unistd.h> + +#include <grpc/support/log.h> +#include <grpc/support/sync.h> + +static __thread char magic_thread_local; + +static long ncpus = 0; + +static void init_ncpus() { + ncpus = sysconf(_SC_NPROCESSORS_ONLN); + if (ncpus < 1 || ncpus > INT32_MAX) { + 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 (unsigned)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 (unsigned)shard_ptr(&magic_thread_local); +} + +#endif /* GPR_CPU_POSIX */ |