Attempt mmap-based in-place huge reallocation.

Attempt mmap-based in-place huge reallocation by plumbing new_addr into
chunk_alloc_mmap().  This can dramatically speed up incremental huge
reallocation.

This resolves #335.

3 files changed, 12 insertions, 13 deletions

diff --git a/include/jemalloc/internal/chunk_mmap.h b/include/jemalloc/internal/chunk_mmap.h
index 7d8014c..6f2d0ac 100644
--- a/include/jemalloc/internal/chunk_mmap.h
+++ b/include/jemalloc/internal/chunk_mmap.h
@@ -9,8 +9,8 @@
 /******************************************************************************/
 #ifdef JEMALLOC_H_EXTERNS
 
-void	*chunk_alloc_mmap(size_t size, size_t alignment, bool *zero,
-    bool *commit);
+void	*chunk_alloc_mmap(void *new_addr, size_t size, size_t alignment,
+    bool *zero, bool *commit);
 bool	chunk_dalloc_mmap(void *chunk, size_t size);
 
 #endif /* JEMALLOC_H_EXTERNS */
diff --git a/src/chunk.c b/src/chunk.c
index 9de36eb..6a107e1 100644
--- a/src/chunk.c
+++ b/src/chunk.c
@@ -350,12 +350,9 @@ chunk_alloc_core(arena_t *arena, void *new_addr, size_t size, size_t alignment,
 	    chunk_alloc_dss(arena, new_addr, size, alignment, zero, commit)) !=
 	    NULL)
 		return (ret);
-	/*
-	 * mmap.  Requesting an address is not implemented for
-	 * chunk_alloc_mmap(), so only call it if (new_addr == NULL).
-	 */
-	if (new_addr == NULL && (ret = chunk_alloc_mmap(size, alignment, zero,
-	    commit)) != NULL)
+	/* mmap. */
+	if ((ret = chunk_alloc_mmap(new_addr, size, alignment, zero, commit)) !=
+	    NULL)
 		return (ret);
 	/* "secondary" dss. */
 	if (have_dss && dss_prec == dss_prec_secondary && (ret =
@@ -380,7 +377,7 @@ chunk_alloc_base(size_t size)
 	 */
 	zero = true;
 	commit = true;
-	ret = chunk_alloc_mmap(size, chunksize, &zero, &commit);
+	ret = chunk_alloc_mmap(NULL, size, chunksize, &zero, &commit);
 	if (ret == NULL)
 		return (NULL);
 	if (config_valgrind)
diff --git a/src/chunk_mmap.c b/src/chunk_mmap.c
index b9ba741..56b2ee4 100644
--- a/src/chunk_mmap.c
+++ b/src/chunk_mmap.c
@@ -32,7 +32,8 @@ chunk_alloc_mmap_slow(size_t size, size_t alignment, bool *zero, bool *commit)
 }
 
 void *
-chunk_alloc_mmap(size_t size, size_t alignment, bool *zero, bool *commit)
+chunk_alloc_mmap(void *new_addr, size_t size, size_t alignment, bool *zero,
+    bool *commit)
 {
 	void *ret;
 	size_t offset;
@@ -53,9 +54,10 @@ chunk_alloc_mmap(size_t size, size_t alignment, bool *zero, bool *commit)
 	assert(alignment != 0);
 	assert((alignment & chunksize_mask) == 0);
 
-	ret = pages_map(NULL, size);
-	if (ret == NULL)
-		return (NULL);
+	ret = pages_map(new_addr, size);
+	if (ret == NULL || ret == new_addr)
+		return (ret);
+	assert(new_addr == NULL);
 	offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
 	if (offset != 0) {
 		pages_unmap(ret, size);