From b42a214c1807dc596cf3647fc35a0eb42ccc7e68 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@redhat.com>
Date: Mon, 24 Aug 2009 16:23:47 -0700
Subject: Hint to kernel that thread stack memory can be removed.

---
 nptl/pthread_create.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'nptl/pthread_create.c')

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index c693979..89938b3 100644
--- a/nptl/pthread_create.c
+++ b/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.  */
-- 
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