diff options
| -rw-r--r-- | Makefile.am | 1 | ||||
| -rw-r--r-- | src/util/HugeAllocator.cxx | 87 | ||||
| -rw-r--r-- | src/util/HugeAllocator.hxx | 82 |
3 files changed, 170 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am index 8130d6fc4..eaba44331 100644 --- a/Makefile.am +++ b/Makefile.am @@ -348,6 +348,7 @@ endif libutil_a_SOURCES = \ src/util/SliceBuffer.hxx \ + src/util/HugeAllocator.cxx src/util/HugeAllocator.hxx \ src/util/list.h \ src/util/list_sort.c src/util/list_sort.h \ src/util/byte_reverse.c src/util/byte_reverse.h \ diff --git a/src/util/HugeAllocator.cxx b/src/util/HugeAllocator.cxx new file mode 100644 index 000000000..d1c55c965 --- /dev/null +++ b/src/util/HugeAllocator.cxx @@ -0,0 +1,87 @@ +/* + * Copyright (C) 2003-2013 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 diff --git a/src/util/HugeAllocator.hxx b/src/util/HugeAllocator.hxx new file mode 100644 index 000000000..01c92cd43 --- /dev/null +++ b/src/util/HugeAllocator.hxx @@ -0,0 +1,82 @@ +/* + * Copyright (C) 2003-2013 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. + */ + +#ifndef MPD_HUGE_ALLOCATOR_HXX +#define MPD_HUGE_ALLOCATOR_HXX + +#include "gcc.h" + +#include <stddef.h> + +#ifdef __linux__ + +/** + * Allocate a huge amount of memory. This will be done in a way that + * allows giving the memory back to the kernel as soon as we don't + * need it anymore. On the downside, this call is expensive. + */ +gcc_malloc +void * +HugeAllocate(size_t size); + +/** + * @param p an allocation returned by HugeAllocate() + * @param size the allocation's size as passed to HugeAllocate() + */ +void +HugeFree(void *p, size_t size); + +/** + * Discard any data stored in the allocation and give the memory back + * to the kernel. After returning, the allocation still exists and + * can be reused at any time, but its contents are undefined. + * + * @param p an allocation returned by HugeAllocate() + * @param size the allocation's size as passed to HugeAllocate() + */ +void +HugeDiscard(void *p, size_t size); + +#else + +/* not Linux: fall back to standard C calls */ + +#include <stdlib.h> + +gcc_malloc +static inline void * +HugeAllocate(size_t size) +{ + return malloc(size); +} + +static inline void +HugeFree(void *p, size_t) +{ + free(p); +} + +static inline void +HugeDiscard(void *, size_t) +{ +} + +#endif + +#endif |