add another SMP assertion

[ghc-hetmet.git] / ghc / rts / MBlock.c

diff --git a/ghc/rts/MBlock.c b/ghc/rts/MBlock.c
index 0ce1e76..8e07ee5 100644 (file)
--- a/ghc/rts/MBlock.c
+++ b/ghc/rts/MBlock.c
@@ -134,6 +134,16 @@ getMBlock(void)
    chunk, on the grounds that this is aligned and likely to be free.
    If it turns out that we were wrong, we have to munmap() and try
    again using the general method.
+
+   Note on posix_memalign(): this interface is available on recent
+   systems and appears to provide exactly what we want.  However, it
+   turns out not to be as good as our mmap() implementation, because
+   it wastes extra space (using double the address space, in a test on
+   x86_64/Linux).  The problem seems to be that posix_memalign()
+   returns memory that can be free()'d, so the library must store
+   extra information along with the allocated block, thus messing up
+   the alignment.  Hence, we don't use posix_memalign() for now.
+
    -------------------------------------------------------------------------- */
 
 #if !defined(mingw32_HOST_OS) && !defined(cygwin32_HOST_OS)
@@ -171,10 +181,14 @@ my_mmap (void *addr, lnat size)
     if(!addr || err)   // try to allocate anywhere
        err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, TRUE);
        
-    if(err) // don't know what the error codes mean exactly
-       barf("memory allocation failed (requested %lu bytes)", size);
-    else
+    if(err) {
+       // don't know what the error codes mean exactly, assume it's
+       // not our problem though.
+       errorBelch("memory allocation failed (requested %lu bytes)", size);
+       stg_exit(EXIT_FAILURE);
+    } else {
        vm_protect(mach_task_self(),ret,size,FALSE,VM_PROT_READ|VM_PROT_WRITE);
+    }
 #else
     ret = mmap(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC, 
               MAP_ANON | MAP_PRIVATE, -1, 0);