Changeset 9a3b469 in mainline

Timestamp:

2012-12-04T04:09:08Z (11 years ago)

Author:

Adam Hraska <adam.hraska+hos@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

d54b303

Parents:

1b7eec9

Message:

malloc avoids using futexes during initialization of the main thread of a program.

Location:

uspace/lib/c/generic

Files:

• libc.c (modified) (2 diffs)
• malloc.c (modified) (3 diffs)
• private/thread.h (modified) (1 diff)
• thread.c (modified) (2 diffs)

uspace/lib/c/generic/libc.c

@@ -51 +51 @@
 #include "private/malloc.h"
 #include "private/io.h"
+#include "private/thread.h"
 
 #ifdef CONFIG_RTLD
@@ -72 +73 @@
         /* Save the PCB pointer */
         __pcb = (pcb_t *) pcb_ptr;
+        
+        atomic_inc(&_created_thread_cnt);
         
         /* The basic run-time environment is setup */

uspace/lib/c/generic/malloc.c

@@ -47 +47 @@
 #include <adt/gcdlcm.h>
 #include "private/malloc.h"
+#include "private/thread.h"
 
 /** Magic used in heap headers. */
@@ -785 +786 @@
 void *malloc(const size_t size)
 {
-        futex_down(&malloc_futex);
-        void *block = malloc_internal(size, BASE_ALIGN);
-        futex_up(&malloc_futex);
-        
-        return block;
+        /* Do not use futexes for allocations during main thread initialization. */
+        if (0 == atomic_get(&_created_thread_cnt)) {
+                return malloc_internal(size, BASE_ALIGN);
+        } else {
+                futex_down(&malloc_futex);
+                void *block = malloc_internal(size, BASE_ALIGN);
+                futex_up(&malloc_futex);
+                return block;
+        }
 }
 
@@ -807 +812 @@
         size_t palign =
             1 << (fnzb(max(sizeof(void *), align) - 1) + 1);
-        
-        futex_down(&malloc_futex);
-        void *block = malloc_internal(size, palign);
-        futex_up(&malloc_futex);
-        
-        return block;
+
+        /* Do not use futexes for allocations during main thread initialization. */
+        if (0 == atomic_get(&_created_thread_cnt)) {
+                return malloc_internal(size, palign);
+        } else {
+                futex_down(&malloc_futex);
+                void *block = malloc_internal(size, palign);
+                futex_up(&malloc_futex);
+
+                return block;
+        }
 }
 

uspace/lib/c/generic/private/thread.h

@@ -41 +41 @@
 extern void __thread_main(uspace_arg_t *);
 
+struct atomic;
+extern struct atomic _created_thread_cnt;
+
 #endif
 

uspace/lib/c/generic/thread.c

@@ -46 +46 @@
 #include "private/thread.h"
 
+/** 
+ * The number of threads that have been created and initialized since 
+ * the start of the program. 
+ */
+atomic_t _created_thread_cnt = {0};
+
 /** Main thread function.
  *
@@ -62 +68 @@
         
         __tcb_set(fibril->tcb);
+        
+        atomic_inc(&_created_thread_cnt);
         
         uarg->uspace_thread_function(uarg->uspace_thread_arg);