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mirror of https://gitlab.nic.cz/labs/bird.git synced 2024-12-22 17:51:53 +00:00
bird/sysdep/unix/alloc.c
Maria Matejka da8a23277e CLI: Dumping internal data structures to files, not to debug output
All the 'dump something' CLI commands now have a new mandatory
argument -- name of the file where to dump the data. This allows
for more flexible dumping even for production deployments where
the debug output is by default off.

Also the dump commands are now restricted (they weren't before)
to assure that only the appropriate users can run these time consuming
commands.
2024-12-02 06:54:54 +01:00

285 lines
7.1 KiB
C

/*
* 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 CONFIG_DISABLE_THP
#include <sys/prctl.h>
#ifndef PR_SET_THP_DISABLE
#define PR_SET_THP_DISABLE 41
#endif
#endif
long page_size = 0;
#ifdef HAVE_MMAP
#define KEEP_PAGES_MAIN_MAX 256
#define KEEP_PAGES_MAIN_MIN 8
#define CLEANUP_PAGES_BULK 256
STATIC_ASSERT(KEEP_PAGES_MAIN_MIN * 4 < KEEP_PAGES_MAIN_MAX);
static bool use_fake = 0;
#if DEBUGGING
struct free_page {
node unused[42];
node n;
};
#else
struct free_page {
node n;
};
#endif
#define EP_POS_MAX ((page_size - OFFSETOF(struct empty_pages, pages)) / sizeof (void *))
struct empty_pages {
node n;
uint pos;
void *pages[0];
};
struct free_pages {
list pages; /* List of (struct free_page) keeping free pages without releasing them (hot) */
list empty; /* List of (struct empty_pages) keeping invalidated pages mapped for us (cold) */
u16 min, max; /* Minimal and maximal number of free pages kept */
uint cnt; /* Number of free pages in list */
event cleanup;
};
static void global_free_pages_cleanup_event(void *);
static void *alloc_cold_page(void);
static struct free_pages global_free_pages = {
.min = KEEP_PAGES_MAIN_MIN,
.max = KEEP_PAGES_MAIN_MAX,
.cleanup = { .hook = global_free_pages_cleanup_event },
};
uint *pages_kept = &global_free_pages.cnt;
static void *
alloc_sys_page(void)
{
void *ptr = mmap(NULL, page_size, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (ptr == MAP_FAILED)
die("mmap(%ld) failed: %m", (s64) page_size);
return ptr;
}
extern int shutting_down; /* Shutdown requested. */
#else // ! HAVE_MMAP
#define use_fake 1
#endif
void *
alloc_page(void)
{
/* If the system page allocator is goofy, we use posix_memalign to get aligned blocks of memory. */
if (use_fake)
{
void *ptr = NULL;
int err = posix_memalign(&ptr, page_size, page_size);
if (err || !ptr)
die("posix_memalign(%ld) failed", (s64) page_size);
return ptr;
}
#ifdef HAVE_MMAP
struct free_pages *fps = &global_free_pages;
/* If there is any free page kept hot, we use it. */
if (fps->cnt)
{
struct free_page *fp = SKIP_BACK(struct free_page, n, HEAD(fps->pages));
rem_node(&fp->n);
/* If the hot-free-page cache is getting short, request the cleanup routine to replenish the cache */
if ((--fps->cnt < fps->min) && !shutting_down)
ev_schedule(&fps->cleanup);
return fp;
}
else
return alloc_cold_page();
}
static void *
alloc_cold_page(void)
{
struct free_pages *fps = &global_free_pages;
/* If there is any free page kept cold, we use that. */
if (!EMPTY_LIST(fps->empty))
{
struct empty_pages *ep = HEAD(fps->empty);
/* Either the keeper page contains at least one cold page pointer, return that */
if (ep->pos)
return ep->pages[--ep->pos];
/* Or the keeper page has no more cold page pointer, return the keeper page */
rem_node(&ep->n);
return ep;
}
/* And in the worst case, allocate a new page by mmap() */
return alloc_sys_page();
#endif
}
void
free_page(void *ptr)
{
/* If the system page allocator is goofy, we just free the block and care no more. */
if (use_fake)
{
free(ptr);
return;
}
#ifdef HAVE_MMAP
struct free_pages *fps = &global_free_pages;
struct free_page *fp = ptr;
/* Otherwise, we add the free page to the hot-free-page list */
fp->n = (node) {};
add_tail(&fps->pages, &fp->n);
/* And if there are too many hot free pages, we ask for page cleanup */
if ((++fps->cnt > fps->max) && !shutting_down)
ev_schedule(&fps->cleanup);
#endif
}
#ifdef HAVE_MMAP
static void
global_free_pages_cleanup_event(void *data UNUSED)
{
/* Cleanup on shutdown is ignored. All pages may be kept hot, OS will take care. */
if (shutting_down)
return;
struct free_pages *fps = &global_free_pages;
/* Cleanup may get called when hot free page cache is short of pages. Replenishing. */
while (fps->cnt / 2 < fps->min)
free_page(alloc_cold_page());
/* Or the hot free page cache is too big. Moving some pages to the cold free page cache. */
for (int limit = CLEANUP_PAGES_BULK; limit && (fps->cnt > fps->max / 2); fps->cnt--, limit--)
{
struct free_page *fp = SKIP_BACK(struct free_page, n, TAIL(fps->pages));
rem_node(&fp->n);
/* Empty pages are stored as pointers. To store them, we need a pointer block. */
struct empty_pages *ep;
if (EMPTY_LIST(fps->empty) || ((ep = HEAD(fps->empty))->pos == EP_POS_MAX))
{
/* There is either no pointer block or the last block is full. We use this block as a pointer block. */
ep = (struct empty_pages *) fp;
*ep = (struct empty_pages) {};
add_head(&fps->empty, &ep->n);
}
else
{
/* We store this block as a pointer into the first free place
* and tell the OS that the underlying memory is trash. */
ep->pages[ep->pos++] = fp;
if (madvise(fp, page_size,
#ifdef CONFIG_MADV_DONTNEED_TO_FREE
MADV_DONTNEED
#else
MADV_FREE
#endif
) < 0)
bug("madvise(%p) failed: %m", fp);
}
}
/* If the hot free page cleanup hit the limit, re-schedule this routine
* to allow for other routines to run. */
if (fps->cnt > fps->max)
ev_schedule(&fps->cleanup);
}
#endif
void
page_dump(struct dump_request *dreq)
{
#ifdef HAVE_MMAP
RDUMP("Hot pages:\n");
node *n;
WALK_LIST(n, global_free_pages.pages)
RDUMP(" %p\n", n);
RDUMP("Cold pages:\n");
WALK_LIST(n, global_free_pages.empty)
{
struct empty_pages *ep = SKIP_BACK(struct empty_pages, n, n);
RDUMP(" %p (index)\n", ep);
for (uint i=0; i<ep->pos; i++)
RDUMP(" %p\n", ep->pages[i]);
}
#endif
}
void
resource_sys_init(void)
{
#ifdef CONFIG_DISABLE_THP
/* Disable transparent huge pages, they do not work properly with madvice(MADV_DONTNEED) */
if (prctl(PR_SET_THP_DISABLE, (unsigned long) 1, (unsigned long) 0, (unsigned long) 0, (unsigned long) 0) < 0)
log(L_WARN "Cannot disable transparent huge pages: prctl(PR_SET_THP_DISABLE) failed: %m");
#endif
#ifdef HAVE_MMAP
ASSERT_DIE(global_free_pages.cnt == 0);
/* Check what page size the system supports */
if (!(page_size = sysconf(_SC_PAGESIZE)))
die("System page size must be non-zero");
if ((u64_popcount(page_size) == 1) && (page_size >= (1 << 10)) && (page_size <= (1 << 18)))
{
/* We assume that page size has only one bit and is between 1K and 256K (incl.).
* Otherwise, the assumptions in lib/slab.c (sl_head's num_full range) aren't met. */
struct free_pages *fps = &global_free_pages;
init_list(&fps->pages);
init_list(&fps->empty);
global_free_pages_cleanup_event(NULL);
return;
}
/* Too big or strange page, use the aligned allocator instead */
log(L_WARN "Got strange memory page size (%ld), using the aligned allocator instead", (s64) page_size);
use_fake = 1;
#endif
page_size = 4096;
}