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/* 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;
}
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