Hint to kernel that thread stack memory can be removed.

nptl/ChangeLog

@@ -1,3 +1,9 @@
+2009-08-24  Ulrich Drepper  <drepper@redhat.com>
+
+	* pthread_create.c (start_thread): Hint to the kernel that memory for
+	the stack can be reused.  We do not mark all the memory.  The part
+	still in use and some reserve are kept.
+
 2009-08-23  Ulrich Drepper  <drepper@redhat.com>
 
 	* sysdeps/unix/sysv/linux/bits/posix_opt.h: Clean up namespace.
@@ -1847,9 +1853,9 @@
 	* sysdeps/unix/sysv/linux/sh/bits/pthreadtypes.h: Include endian.h.
 	Split __flags into __flags, __shared, __pad1 and __pad2.
 	* sysdeps/unix/sysv/linux/sh/libc-lowlevellock.S: Use private
-        futexes if they are available.
+	futexes if they are available.
 	* sysdeps/unix/sysv/linux/sh/lowlevellock.S: Adjust so that change
-        in libc-lowlevellock.S allow using private futexes.
+	in libc-lowlevellock.S allow using private futexes.
 	* sysdeps/unix/sysv/linux/sh/lowlevellock.h: Define
 	FUTEX_PRIVATE_FLAG.  Add additional parameter to lll_futex_wait,
 	lll_futex_timed_wait and lll_futex_wake.  Change lll_futex_wait
@@ -1857,12 +1863,12 @@
 	lll_private_futex_timed_wait and lll_private_futex_wake.
 	(lll_robust_mutex_unlock): Fix typo.
 	* sysdeps/unix/sysv/linux/sh/pthread_barrier_wait.S: Use private
-        field in futex command setup.
+	field in futex command setup.
 	* sysdeps/unix/sysv/linux/sh/pthread_cond_timedwait.S: Use
 	COND_NWAITERS_SHIFT instead of COND_CLOCK_BITS.
 	* sysdeps/unix/sysv/linux/sh/pthread_cond_wait.S: Likewise.
 	* sysdeps/unix/sysv/linux/sh/pthread_once.S: Use private futexes
-        if they are available.  Remove clear_once_control.
+	if they are available.  Remove clear_once_control.
 	* sysdeps/unix/sysv/linux/sh/pthread_rwlock_rdlock.S: Use private
 	futexes if they are available.
 	* sysdeps/unix/sysv/linux/sh/pthread_rwlock_timedrdlock.S: Likewise.
@@ -1873,7 +1879,7 @@
 	Wake only when there are waiters.
 	* sysdeps/unix/sysv/linux/sh/sem_wait.S: Add private futex
 	support.  Indicate that there are waiters.  Remove unnecessary
-        extra cancellation test.
+	extra cancellation test.
 	* sysdeps/unix/sysv/linux/sh/sem_timedwait.S: Likewise.  Removed
 	left-over duplication of __sem_wait_cleanup.
 
@@ -2587,14 +2593,14 @@
 	* tst-cancel25.c: New file.
 
 2006-09-05  Jakub Jelinek  <jakub@redhat.com>
-            Ulrich Drepper  <drepper@redhat.com>
+	    Ulrich Drepper  <drepper@redhat.com>
 
 	* sysdeps/pthread/gai_misc.h (GAI_MISC_NOTIFY): Don't decrement
 	counterp if it is already zero.
 	* sysdeps/pthread/aio_misc.h (AIO_MISC_NOTIFY): Likewise..
 
 2006-03-04  Jakub Jelinek  <jakub@redhat.com>
-            Roland McGrath  <roland@redhat.com>
+	    Roland McGrath  <roland@redhat.com>
 
 	* sysdeps/unix/sysv/linux/i386/lowlevellock.h
 	(LLL_STUB_UNWIND_INFO_START, LLL_STUB_UNWIND_INFO_END,
@@ -2608,7 +2614,7 @@
 	* sysdeps/unix/sysv/linux/i386/i486/lowlevelrobustlock.S: Likewise.
 
 2006-03-03  Jakub Jelinek  <jakub@redhat.com>
-            Roland McGrath  <roland@redhat.com>
+	    Roland McGrath  <roland@redhat.com>
 
 	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
 	(LLL_STUB_UNWIND_INFO_START, LLL_STUB_UNWIND_INFO_END,
@@ -3181,7 +3187,7 @@
 	* sysdeps/pthread/pthread.h: Adjust mutex initializers.
 
 	* sysdeps/unix/sysv/linux/i386/not-cancel.h: Define openat_not_cancel,
-        openat_not_cancel_3, openat64_not_cancel, and openat64_not_cancel_3.
+	openat_not_cancel_3, openat64_not_cancel, and openat64_not_cancel_3.
 
 2006-02-08  Jakub Jelinek  <jakub@redhat.com>
 
@@ -3603,7 +3609,7 @@
 	* Makefile ($(test-modules)): Remove static pattern rule.
 
 2005-10-14  Jakub Jelinek  <jakub@redhat.com>
-            Ulrich Drepper  <drepper@redhat.com>
+	    Ulrich Drepper  <drepper@redhat.com>
 
 	* sysdeps/unix/sysv/linux/x86_64/pthread_once.S: Fix stack
 	alignment in callback function.
@@ -3621,7 +3627,7 @@
 	atomic_compare_and_exchange_bool_acq.
 
 2005-10-01  Ulrich Drepper  <drepper@redhat.com>
-            Jakub Jelinek  <jakub@redhat.com>
+	    Jakub Jelinek  <jakub@redhat.com>
 
 	* descr.h: Define SETXID_BIT and SETXID_BITMASK.  Adjust
 	CANCEL_RESTMASK.

nptl/pthread_create.c

@@ -377,6 +377,19 @@ start_thread (void *arg)
     }
 #endif
 
+  /* Mark the memory of the stack as usable to the kernel.  We free
+     everything except for the space used for the TCB itself.  */
+  size_t pagesize_m1 = __getpagesize () - 1;
+#ifdef _STACK_GROWS_DOWN
+  char *sp = CURRENT_STACK_FRAME;
+  size_t freesize = (sp - (char *) pd->stackblock) & ~pagesize_m1;
+#else
+# error "to do"
+#endif
+  assert (freesize < pd->stackblock_size);
+  if (freesize > PTHREAD_STACK_MIN)
+    madvise (pd->stackblock, freesize - PTHREAD_STACK_MIN, MADV_DONTNEED);
+
   /* If the thread is detached free the TCB.  */
   if (IS_DETACHED (pd))
     /* Free the TCB.  */