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Diffstat (limited to 'sysdeps/loongarch/cpu-tunables.c')
| -rw-r--r-- | sysdeps/loongarch/cpu-tunables.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/sysdeps/loongarch/cpu-tunables.c b/sysdeps/loongarch/cpu-tunables.c new file mode 100644 index 0000000000..e274e993c1 --- /dev/null +++ b/sysdeps/loongarch/cpu-tunables.c @@ -0,0 +1,87 @@ +/* LoongArch CPU feature tuning. + This file is part of the GNU C Library. + Copyright (C) 2024 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <stdbool.h> +#include <stdint.h> +#include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */ +#include <elf/dl-tunables.h> +#include <string.h> +#include <cpu-features.h> +#include <ldsodefs.h> +#include <sys/auxv.h> +#include <dl-tunables-parse.h> +#include <dl-symbol-redir-ifunc.h> + +#define CHECK_GLIBC_IFUNC_CPU(f, name, len) \ + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \ + if (tunable_str_comma_strcmp_cte (&f, #name)) \ + { \ + if (f.disable) \ + GLRO(dl_larch_cpu_features).hwcap &= (~HWCAP_LOONGARCH_##name); \ + else \ + GLRO(dl_larch_cpu_features).hwcap |= HWCAP_LOONGARCH_##name; \ + break; \ + } + +attribute_hidden void +TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp) +{ + /* The current IFUNC selection is based on microbenchmarks in glibc. + It should give the best performance for most workloads. But other + choices may have better performance for a particular workload or on + the hardware which wasn't available when the selection was made. + The environment variable: + + GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,-zzz,.... + + can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature + yyy and zzz, where the feature name is case-sensitive and has to + match the ones in cpu-features.h. It can be used by glibc developers + to tune for a new processor or override the IFUNC selection to + improve performance for a particular workload. + + NOTE: the IFUNC selection may change over time. Please check all + multiarch implementations when experimenting. */ + + struct tunable_str_comma_state_t ts; + tunable_str_comma_init (&ts, valp); + + struct tunable_str_comma_t n; + while (tunable_str_comma_next (&ts, &n)) + { + switch (n.len) + { + default: + break; + case 3: + { + CHECK_GLIBC_IFUNC_CPU (n, LSX, 3); + CHECK_GLIBC_IFUNC_CPU (n, UAL, 3); + } + break; + case 4: + { + CHECK_GLIBC_IFUNC_CPU (n, LASX, 4); + } + break; + } + } + + /* Ensure that the user has not enabled any unsupported features. */ + GLRO(dl_larch_cpu_features).hwcap &= GLRO(dl_hwcap); +} |