diff options
Diffstat (limited to 'sysdeps/unix/sysv')
-rw-r--r-- | sysdeps/unix/sysv/linux/malloc-hugepages.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/malloc-hugepages.c b/sysdeps/unix/sysv/linux/malloc-hugepages.c new file mode 100644 index 0000000000..7497e07260 --- /dev/null +++ b/sysdeps/unix/sysv/linux/malloc-hugepages.c @@ -0,0 +1,74 @@ +/* Huge Page support. Linux implementation. + Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + 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; see the file COPYING.LIB. If + not, see <https://www.gnu.org/licenses/>. */ + +#include <intprops.h> +#include <malloc-hugepages.h> +#include <not-cancel.h> + +unsigned long int +__malloc_default_thp_pagesize (void) +{ + int fd = __open64_nocancel ( + "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", O_RDONLY); + if (fd == -1) + return 0; + + char str[INT_BUFSIZE_BOUND (unsigned long int)]; + ssize_t s = __read_nocancel (fd, str, sizeof (str)); + __close_nocancel (fd); + if (s < 0) + return 0; + + unsigned long int r = 0; + for (ssize_t i = 0; i < s; i++) + { + if (str[i] == '\n') + break; + r *= 10; + r += str[i] - '0'; + } + return r; +} + +enum malloc_thp_mode_t +__malloc_thp_mode (void) +{ + int fd = __open64_nocancel ("/sys/kernel/mm/transparent_hugepage/enabled", + O_RDONLY); + if (fd == -1) + return malloc_thp_mode_not_supported; + + static const char mode_always[] = "[always] madvise never\n"; + static const char mode_madvise[] = "always [madvise] never\n"; + static const char mode_never[] = "always madvise [never]\n"; + + char str[sizeof(mode_always)]; + ssize_t s = __read_nocancel (fd, str, sizeof (str)); + __close_nocancel (fd); + + if (s == sizeof (mode_always) - 1) + { + if (strcmp (str, mode_always) == 0) + return malloc_thp_mode_always; + else if (strcmp (str, mode_madvise) == 0) + return malloc_thp_mode_madvise; + else if (strcmp (str, mode_never) == 0) + return malloc_thp_mode_never; + } + return malloc_thp_mode_not_supported; +} |