Add huge page configuration and pages_[no}huge().

Add the --with-lg-hugepage configure option, but automatically configure
LG_HUGEPAGE even if it isn't specified.

Add the pages_[no]huge() functions, which toggle huge page state via
madvise(..., MADV_[NO]HUGEPAGE) calls.

include/jemalloc/internal/jemalloc_internal.h.in

@@ -138,6 +138,13 @@ static const bool config_cache_oblivious =
     false
 #endif
     ;
+static const bool have_thp =
+#ifdef JEMALLOC_THP
+    true
+#else
+    false
+#endif
+    ;
 
 #if defined(JEMALLOC_C11ATOMICS) && !defined(__cplusplus)
 #include <stdatomic.h>

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -187,6 +187,13 @@
 /* One page is 2^LG_PAGE bytes. */
 #undef LG_PAGE
 
+/*
+ * One huge page is 2^LG_HUGEPAGE bytes.  Note that this is defined even if the
+ * system does not explicitly support huge pages; system calls that require
+ * explicit huge page support are separately configured.
+ */
+#undef LG_HUGEPAGE
+
 /*
  * If defined, adjacent virtual memory mappings with identical attributes
  * automatically coalesce, and they fragment when changes are made to subranges.
@@ -262,6 +269,12 @@
 #undef JEMALLOC_PURGE_MADVISE_FREE
 #undef JEMALLOC_PURGE_MADVISE_DONTNEED
 
+/*
+ * Defined if transparent huge pages are supported via the MADV_[NO]HUGEPAGE
+ * arguments to madvise(2).
+ */
+#undef JEMALLOC_THP
+
 /* Define if operating system has alloca.h header. */
 #undef JEMALLOC_HAS_ALLOCA_H
 

include/jemalloc/internal/pages.h

@@ -7,15 +7,23 @@
 #endif
 #define	PAGE		((size_t)(1U << LG_PAGE))
 #define	PAGE_MASK	((size_t)(PAGE - 1))
-
 /* Return the page base address for the page containing address a. */
 #define	PAGE_ADDR2BASE(a)						\
 	((void *)((uintptr_t)(a) & ~PAGE_MASK))
-
 /* Return the smallest pagesize multiple that is >= s. */
 #define	PAGE_CEILING(s)							\
 	(((s) + PAGE_MASK) & ~PAGE_MASK)
 
+/* Huge page size.  LG_HUGEPAGE is determined by the configure script. */
+#define	HUGEPAGE	((size_t)(1U << LG_HUGEPAGE))
+#define	HUGEPAGE_MASK	((size_t)(HUGEPAGE - 1))
+/* Return the huge page base address for the huge page containing address a. */
+#define	HUGEPAGE_ADDR2BASE(a)						\
+	((void *)((uintptr_t)(a) & ~HUGEPAGE_MASK))
+/* Return the smallest pagesize multiple that is >= s. */
+#define	HUGEPAGE_CEILING(s)						\
+	(((s) + HUGEPAGE_MASK) & ~HUGEPAGE_MASK)
+
 #endif /* JEMALLOC_H_TYPES */
 /******************************************************************************/
 #ifdef JEMALLOC_H_STRUCTS
@@ -31,6 +39,8 @@ void	*pages_trim(void *addr, size_t alloc_size, size_t leadsize,
 bool	pages_commit(void *addr, size_t size);
 bool	pages_decommit(void *addr, size_t size);
 bool	pages_purge(void *addr, size_t size);
+bool	pages_huge(void *addr, size_t size);
+bool	pages_nohuge(void *addr, size_t size);
 void	pages_boot(void);
 
 #endif /* JEMALLOC_H_EXTERNS */

include/jemalloc/internal/private_symbols.txt

@@ -324,7 +324,9 @@ opt_zero
 pages_boot
 pages_commit
 pages_decommit
+pages_huge
 pages_map
+pages_nohuge
 pages_purge
 pages_trim
 pages_unmap