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88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/* Copyright (C) 2012-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stddef.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sched.h>
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#include <sysdep.h>
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#include <arch/spr_def.h>
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/* The count of cores horizontally (X dimension) on the chip. */
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static int chip_width;
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/* Read the chip "width" from the /sys filesystem. */
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static int
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initialize_chip_width (void)
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{
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int w = 0;
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int fd;
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fd = __open ("/sys/devices/system/cpu/chip_width", O_RDONLY);
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if (fd >= 0)
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{
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char buf[64];
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ssize_t n;
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int i;
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n = __read (fd, buf, sizeof (buf));
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__close (fd);
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for (i = 0; i < n; ++i)
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{
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if (buf[i] < '0' || buf[i] > '9')
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break;
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w = (w * 10) + (buf[i] - '0');
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}
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}
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/* Store a negative value so we don't try again. */
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if (w == 0)
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w = -1;
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/* Using an atomic idempotent write here makes this thread-safe. */
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chip_width = w;
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return w;
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}
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int
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sched_getcpu (void)
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{
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unsigned int coord;
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int w = chip_width;
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if (__builtin_expect (w <= 0, 0))
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{
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if (w == 0)
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w = initialize_chip_width ();
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if (w < 0)
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{
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unsigned int cpu;
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int r = INLINE_SYSCALL (getcpu, 3, &cpu, NULL, NULL);
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return r == -1 ? r : cpu;
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}
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}
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/* Assign 64-bit value to a 32-bit variable to ensure 32-bit multiply. */
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coord = __insn_mfspr (SPR_TILE_COORD);
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/* Extract Y coord from bits 7..10 and X coord from bits 18..21. */
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return ((coord >> 7) & 0xf) * w + ((coord >> 18) & 0xf);
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}
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