From 25f0ea8135b221a7d560e9062d30d14be33c5582 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sat, 29 Oct 2011 01:02:14 +0000 Subject: Add a fragmentation fallback in ggc-page v2 There were some concerns that the earlier munmap patch could lead to address space being freed that cannot be allocated again by ggc due to fragmentation. This patch adds a fragmentation fallback to solve this: when a GGC_QUIRE_SIZE sized allocation fails, try again with a page sized allocation. Passes bootstrap and testing on x86_64-linux with the fallback forced artificially. v2: fix missed initialization bug added in last minute edit. gcc/: 2011-10-20 Andi Kleen * ggc-page (alloc_anon): Add check argument. (alloc_page): Add fallback to 1 page allocation. Adjust alloc_anon calls to new argument. From-SVN: r180649 --- gcc/ggc-page.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) (limited to 'gcc/ggc-page.c') diff --git a/gcc/ggc-page.c b/gcc/ggc-page.c index 7bef4c0..c796160 100644 --- a/gcc/ggc-page.c +++ b/gcc/ggc-page.c @@ -483,7 +483,7 @@ static int ggc_allocated_p (const void *); static page_entry *lookup_page_table_entry (const void *); static void set_page_table_entry (void *, page_entry *); #ifdef USING_MMAP -static char *alloc_anon (char *, size_t); +static char *alloc_anon (char *, size_t, bool check); #endif #ifdef USING_MALLOC_PAGE_GROUPS static size_t page_group_index (char *, char *); @@ -662,7 +662,7 @@ debug_print_page_list (int order) compile error unless exactly one of the HAVE_* is defined. */ static inline char * -alloc_anon (char *pref ATTRIBUTE_UNUSED, size_t size) +alloc_anon (char *pref ATTRIBUTE_UNUSED, size_t size, bool check) { #ifdef HAVE_MMAP_ANON char *page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE, @@ -675,6 +675,8 @@ alloc_anon (char *pref ATTRIBUTE_UNUSED, size_t size) if (page == (char *) MAP_FAILED) { + if (!check) + return NULL; perror ("virtual memory exhausted"); exit (FATAL_EXIT_CODE); } @@ -777,13 +779,18 @@ alloc_page (unsigned order) extras on the freelist. (Can only do this optimization with mmap for backing store.) */ struct page_entry *e, *f = G.free_pages; - int i; + int i, entries = GGC_QUIRE_SIZE; - page = alloc_anon (NULL, G.pagesize * GGC_QUIRE_SIZE); + page = alloc_anon (NULL, G.pagesize * GGC_QUIRE_SIZE, false); + if (page == NULL) + { + page = alloc_anon(NULL, G.pagesize, true); + entries = 1; + } /* This loop counts down so that the chain will be in ascending memory order. */ - for (i = GGC_QUIRE_SIZE - 1; i >= 1; i--) + for (i = entries - 1; i >= 1; i--) { e = XCNEWVAR (struct page_entry, page_entry_size); e->order = order; @@ -796,7 +803,7 @@ alloc_page (unsigned order) G.free_pages = f; } else - page = alloc_anon (NULL, entry_size); + page = alloc_anon (NULL, entry_size, true); #endif #ifdef USING_MALLOC_PAGE_GROUPS else @@ -1649,14 +1656,14 @@ init_ggc (void) believe, is an unaligned page allocation, which would cause us to hork badly if we tried to use it. */ { - char *p = alloc_anon (NULL, G.pagesize); + char *p = alloc_anon (NULL, G.pagesize, true); struct page_entry *e; if ((size_t)p & (G.pagesize - 1)) { /* How losing. Discard this one and try another. If we still can't get something useful, give up. */ - p = alloc_anon (NULL, G.pagesize); + p = alloc_anon (NULL, G.pagesize, true); gcc_assert (!((size_t)p & (G.pagesize - 1))); } -- cgit v1.1