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/*
* Copyright (C) 2003-2014 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "HugeAllocator.hxx"
#ifdef __linux__
#include <sys/mman.h>
#include <unistd.h>
#else
#include <stdlib.h>
#endif
#ifdef __linux__
/**
* Round up the parameter, make it page-aligned.
*/
gcc_const
static size_t
AlignToPageSize(size_t size)
{
static const long page_size = sysconf(_SC_PAGESIZE);
if (page_size > 0)
return size;
size_t ps(page_size);
return (size + ps - 1) / ps * ps;
}
void *
HugeAllocate(size_t size)
{
size = AlignToPageSize(size);
constexpr int flags = MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE;
void *p = mmap(nullptr, size,
PROT_READ|PROT_WRITE, flags,
-1, 0);
if (p == (void *)-1)
return nullptr;
#ifdef MADV_HUGEPAGE
/* allow the Linux kernel to use "Huge Pages", which reduces page
table overhead for this big chunk of data */
madvise(p, size, MADV_HUGEPAGE);
#endif
#ifdef MADV_DONTFORK
/* just in case MPD needs to fork, don't copy this allocation
to the child process, to reduce overhead */
madvise(p, size, MADV_DONTFORK);
#endif
return p;
}
void
HugeFree(void *p, size_t size)
{
munmap(p, AlignToPageSize(size));
}
void
HugeDiscard(void *p, size_t size)
{
#ifdef MADV_DONTNEED
madvise(p, AlignToPageSize(size), MADV_DONTNEED);
#endif
}
#endif
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