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Debug: keep a circular log of memory page operations
This commit is contained in:
Maria Matejka
parent
1e998a4349
commit
00f30ac40b
@ -183,6 +183,8 @@ void bug(const char *msg, ...) NORET;
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void debug(const char *msg, ...); /* Printf to debug output */
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void debug_safe(const char *msg); /* Printf to debug output, async-safe */
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extern _Thread_local uint this_thread_id;
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/* Debugging */
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#if defined(LOCAL_DEBUG) || defined(GLOBAL_DEBUG)
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@ -51,14 +51,62 @@ long page_size = 0;
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# define UNPROTECT_PAGE(pg) mprotect((pg), page_size, PROT_READ | PROT_WRITE)
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# endif
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# define AJSIZE 16384
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static struct alloc_journal {
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void *fp;
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void *next;
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u16 pos;
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u16 type;
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uint thread_id;
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} alloc_journal[AJSIZE];
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_Thread_local int alloc_journal_local_pos = -1;
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_Atomic int alloc_journal_pos = 0;
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# define AJT_ALLOC_LOCAL_HOT 1
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# define AJT_ALLOC_GLOBAL_HOT 2
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# define AJT_ALLOC_COLD_STD 3
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# define AJT_ALLOC_COLD_KEEPER 4
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# define AJT_ALLOC_MMAP 5
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# define AJT_FREE_LOCAL_HOT 0x11
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# define AJT_FREE_GLOBAL_HOT 0x12
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# define AJT_CLEANUP_NOTHING 0xc0
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# define AJT_CLEANUP_COLD_STD 0xc3
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# define AJT_CLEANUP_COLD_KEEPER 0xc4
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# define AJT_CLEANUP_BEGIN 0xcb
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# define AJT_CLEANUP_END 0xce
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# define AJT_FLUSH_LOCAL_BEGIN 0xfb
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# define AJT_FLUSH_LOCAL_END 0xfe
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# define AJT_SCHEDULE_CLEANUP 0xff
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static void
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ajlog(void *fp, void *next, u16 pos, u16 type)
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{
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alloc_journal[(alloc_journal_local_pos = atomic_fetch_add_explicit(&alloc_journal_pos, 1, memory_order_relaxed)) % AJSIZE] = (struct alloc_journal) {
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.fp = fp,
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.next = next,
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.pos = pos,
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.type = type,
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.thread_id = this_thread_id,
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};
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}
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struct free_page {
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node unused[42];
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struct free_page * _Atomic next;
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};
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# else
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# else /* ! DEBUGGING */
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# define ajlog(...)
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struct free_page {
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struct free_page * _Atomic next;
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};
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# endif
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# define WRITE_NEXT(pg, val) do { UNPROTECT_PAGE((pg)); atomic_store_explicit(&(pg)->next, (val), memory_order_release); PROTECT_PAGE((pg)); } while (0)
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@ -127,6 +175,7 @@ alloc_page(void)
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atomic_fetch_sub_explicit(&pages_kept_locally, 1, memory_order_relaxed);
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pages_kept_here--;
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UNPROTECT_PAGE(fp);
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ajlog(fp, local_page_stack, pages_kept_here, AJT_ALLOC_LOCAL_HOT);
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return fp;
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}
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@ -141,8 +190,9 @@ alloc_page(void)
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if (fp)
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{
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atomic_fetch_sub_explicit(&pages_kept, 1, memory_order_relaxed);
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uint pk = atomic_fetch_sub_explicit(&pages_kept, 1, memory_order_relaxed);
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UNPROTECT_PAGE(fp);
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ajlog(fp, atomic_load_explicit(&fp->next, memory_order_relaxed), pk, AJT_ALLOC_GLOBAL_HOT);
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return fp;
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}
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@ -156,12 +206,14 @@ alloc_page(void)
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fp = empty_pages->pages[--empty_pages->pos];
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PROTECT_PAGE(empty_pages);
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UNPROTECT_PAGE(fp);
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ajlog(fp, empty_pages, empty_pages->pos, AJT_ALLOC_COLD_STD);
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}
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else
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{
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/* Or the keeper page has no more cold page pointer, return the keeper page */
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fp = (struct free_page *) empty_pages;
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empty_pages = empty_pages->next;
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ajlog(fp, empty_pages, 0, AJT_ALLOC_COLD_KEEPER);
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}
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}
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UNLOCK_DOMAIN(resource, empty_pages_domain);
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@ -171,6 +223,8 @@ alloc_page(void)
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/* And in the worst case, allocate some new pages by mmap() */
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void *ptr = alloc_sys_page();
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ajlog(ptr, NULL, 0, AJT_ALLOC_MMAP);
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for (int i=1; i<ALLOC_PAGES_AT_ONCE; i++)
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free_page(ptr + page_size * i);
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@ -193,12 +247,14 @@ free_page(void *ptr)
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struct free_page *fp = ptr;
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if (shutting_down || (pages_kept_here < KEEP_PAGES_MAX_LOCAL))
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{
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atomic_store_explicit(&fp->next, local_page_stack, memory_order_relaxed);
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struct free_page *next = local_page_stack;
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atomic_store_explicit(&fp->next, next, memory_order_relaxed);
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PROTECT_PAGE(fp);
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local_page_stack = fp;
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atomic_fetch_add_explicit(&pages_kept_locally, 1, memory_order_relaxed);
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pages_kept_here++;
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ajlog(fp, next, pages_kept_here, AJT_FREE_LOCAL_HOT);
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return;
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}
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@ -213,8 +269,11 @@ free_page(void *ptr)
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memory_order_acq_rel, memory_order_acquire))
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WRITE_NEXT(fp, next);
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uint pk = atomic_fetch_add_explicit(&pages_kept, 1, memory_order_relaxed);
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ajlog(fp, next, pk, AJT_FREE_GLOBAL_HOT);
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/* And if there are too many global hot free pages, we ask for page cleanup */
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if (atomic_fetch_add_explicit(&pages_kept, 1, memory_order_relaxed) >= KEEP_PAGES_MAX)
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if (pk >= KEEP_PAGES_MAX)
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SCHEDULE_CLEANUP;
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#endif
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}
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@ -227,6 +286,8 @@ flush_local_pages(void)
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if (use_fake || !local_page_stack || shutting_down)
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return;
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ajlog(local_page_stack, NULL, pages_kept_here, AJT_FLUSH_LOCAL_BEGIN);
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/* We first count the pages to enable consistency checking.
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* Also, we need to know the last page. */
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struct free_page *last = local_page_stack, *next;
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@ -254,6 +315,8 @@ flush_local_pages(void)
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local_page_stack = NULL;
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pages_kept_here = 0;
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ajlog(NULL, NULL, 0, AJT_FLUSH_LOCAL_END);
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/* Check the state of global page cache and maybe schedule its cleanup. */
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atomic_fetch_sub_explicit(&pages_kept_locally, check_count, memory_order_relaxed);
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if (atomic_fetch_add_explicit(&pages_kept, check_count, memory_order_relaxed) >= KEEP_PAGES_MAX)
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@ -268,10 +331,14 @@ page_cleanup(void *_ UNUSED)
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if (shutting_down)
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return;
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ajlog(NULL, NULL, 0, AJT_CLEANUP_BEGIN);
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struct free_page *stack = atomic_exchange_explicit(&page_stack, NULL, memory_order_acq_rel);
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if (!stack)
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{
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ajlog(NULL, NULL, 0, AJT_CLEANUP_NOTHING);
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return;
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}
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do {
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struct free_page *fp = stack;
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@ -289,6 +356,7 @@ page_cleanup(void *_ UNUSED)
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};
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PROTECT_PAGE(ep);
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empty_pages = ep;
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ajlog(empty_pages, empty_pages->next, 0, AJT_CLEANUP_COLD_KEEPER);
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}
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else
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{
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@ -307,6 +375,7 @@ page_cleanup(void *_ UNUSED)
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#endif
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) < 0)
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bug("madvise(%p) failed: %m", fp);
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ajlog(fp, empty_pages, empty_pages->pos, AJT_CLEANUP_COLD_STD);
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}
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UNLOCK_DOMAIN(resource, empty_pages_domain);
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}
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@ -321,6 +390,7 @@ page_cleanup(void *_ UNUSED)
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atomic_fetch_sub_explicit(&pages_kept, 1, memory_order_relaxed);
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}
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ajlog(NULL, NULL, 0, AJT_CLEANUP_END);
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}
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#endif
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@ -38,7 +38,7 @@ static list *current_log_list;
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static char *current_syslog_name; /* NULL -> syslog closed */
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static _Atomic uint max_thread_id = ATOMIC_VAR_INIT(1);
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static _Thread_local uint this_thread_id;
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_Thread_local uint this_thread_id;
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#define THIS_THREAD_ID (this_thread_id ?: (this_thread_id = atomic_fetch_add_explicit(&max_thread_id, 1, memory_order_acq_rel)))
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