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/*
* Copyright (C) 2013 Max Kellermann <max@duempel.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#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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