From: Andi Kleen <a...@linux.intel.com>
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 <a...@linux.intel.com>
* ggc-page (alloc_anon): Add check argument.
(alloc_page): Add fallback to 1 page allocation.
Adjust alloc_anon calls to new argument.
---
gcc/ggc-page.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/gcc/ggc-page.c b/gcc/ggc-page.c
index 99bf2df..0bf0907 100644
--- a/gcc/ggc-page.c
+++ b/gcc/ggc-page.c
@@ -482,7 +482,7 @@ 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 *);
@@ -661,7 +661,7 @@ 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,
@@ -674,6 +674,8 @@ 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);
}
@@ -776,13 +778,18 @@ 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;
@@ -795,7 +802,7 @@ 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
@@ -1648,14 +1655,14 @@ 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)));
}
--
1.7.5.4
