Don't explicitly mmap() red zones at the bottom of thread stacks (except

the initial thread).  Instead, just leave an unmapped gap between thread
stacks and make sure that the thread stacks won't grow into these gaps,
simply by limiting the size of the stacks with the 'len' argument to
mmap().  This (if I understand correctly) reduces VM overhead
considerably.

Reviewed by:	deischen

1 files changed, 1 insertions, 10 deletions

diff --git a/lib/libpthread/thread/thr_create.c b/lib/libpthread/thread/thr_create.c
index a392cba..fd9e746 100644
--- a/lib/libpthread/thread/thr_create.c
+++ b/lib/libpthread/thread/thr_create.c
@@ -136,20 +136,11 @@ pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 				if (pthread_mutex_unlock(&_gc_mutex) != 0)
 					PANIC("Cannot unlock gc mutex");
 
-				/* Red zone: */
-				if (mmap(stack - PTHREAD_STACK_GUARD,
-				    PTHREAD_STACK_GUARD, 0, MAP_ANON,
-				    -1, 0) == MAP_FAILED) {
-					ret = EAGAIN;
-					free(new_thread);
-				}
 				/* Stack: */
-				else if (mmap(stack, PTHREAD_STACK_DEFAULT,
+				if (mmap(stack, PTHREAD_STACK_DEFAULT,
 				    PROT_READ | PROT_WRITE, MAP_STACK,
 				    -1, 0) == MAP_FAILED) {
 					ret = EAGAIN;
-					munmap(stack - PTHREAD_STACK_GUARD,
-					    PTHREAD_STACK_GUARD);
 					free(new_thread);
 				}
 			}