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/*
* BIRD Internet Routing Daemon -- Raw allocation
*
* (c) 2020 Maria Matejka <mq@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "nest/bird.h"
#include "lib/resource.h"
#include "lib/lists.h"
#include "lib/event.h"
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_MMAP
#include <sys/mman.h>
#endif
#ifdef HAVE_MMAP
#define KEEP_PAGES 512
static u64 page_size = 0;
static _Bool use_fake = 0;
uint pages_kept = 0;
static list pages_list;
static void cleanup_pages(void *data);
static event page_cleanup_event = { .hook = cleanup_pages };
#else
static const u64 page_size = 4096; /* Fake page size */
#endif
u64 get_page_size(void)
{
if (page_size)
return page_size;
#ifdef HAVE_MMAP
if (page_size = sysconf(_SC_PAGESIZE))
{
if ((u64_popcount(page_size) > 1) || (page_size > 16384))
{
/* Too big or strange page, use the aligned allocator instead */
page_size = 4096;
use_fake = 1;
}
return page_size;
}
bug("Page size must be non-zero");
#endif
}
void *
alloc_page(void)
{
#ifdef HAVE_MMAP
if (pages_kept)
{
node *page = TAIL(pages_list);
rem_node(page);
pages_kept--;
memset(page, 0, get_page_size());
return page;
}
if (!use_fake)
{
void *ret = mmap(NULL, get_page_size(), PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (ret == MAP_FAILED)
bug("mmap(%lu) failed: %m", (long unsigned int) page_size);
return ret;
}
else
#endif
{
void *ptr = NULL;
int err = posix_memalign(&ptr, page_size, page_size);
if (err || !ptr)
bug("posix_memalign(%lu) failed", (long unsigned int) page_size);
return ptr;
}
}
void
free_page(void *ptr)
{
#ifdef HAVE_MMAP
if (!use_fake)
{
if (!pages_kept)
init_list(&pages_list);
memset(ptr, 0, sizeof(node));
add_tail(&pages_list, ptr);
if (++pages_kept > KEEP_PAGES)
ev_schedule(&page_cleanup_event);
}
else
#endif
free(ptr);
}
#ifdef HAVE_MMAP
static void
cleanup_pages(void *data UNUSED)
{
for (uint seen = 0; (pages_kept > KEEP_PAGES) && (seen < KEEP_PAGES); seen++)
{
void *ptr = HEAD(pages_list);
rem_node(ptr);
if (munmap(ptr, get_page_size()) == 0)
pages_kept--;
else if (errno == ENOMEM)
add_tail(&pages_list, ptr);
else
bug("munmap(%p) failed: %m", ptr);
}
if (pages_kept > KEEP_PAGES)
ev_schedule(&page_cleanup_event);
}
#endif
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