mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-15 04:20:28 +08:00
095067efdf
The current IFUNC selection is always using the most recent features which are available via AT_HWCAP. But in some scenarios it is useful to adjust this selection. The environment variable: GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,zzz,.... can be used to enable HWCAP feature yyy, disable HWCAP feature xxx, where the feature name is case-sensitive and has to match the ones used in sysdeps/loongarch/cpu-tunables.c. Signed-off-by: caiyinyu <caiyinyu@loongson.cn>
88 lines
2.9 KiB
C
88 lines
2.9 KiB
C
/* 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);
|
|
}
|