consolidate WARN_...ONCE() static variables
Jan Beulich [Fri, 23 Mar 2012 22:01:52 +0000 (15:01 -0700)]
Due to the alignment of following variables, these typically consume
more than just the single byte that 'bool' requires, and as there are a
few hundred instances, the cache pollution (not so much the waste of
memory) sums up.  Put these variables into their own section, outside of
any half way frequently used memory range.

Do the same also to the __warned variable of rcu_lockdep_assert().
(Don't, however, include the ones used by printk_once() and alike, as
they can potentially be hot.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-generic/bug.h
include/asm-generic/vmlinux.lds.h
include/linux/rcupdate.h

index 84458b0..2520a6e 100644 (file)
@@ -134,7 +134,7 @@ extern void warn_slowpath_null(const char *file, const int line);
 #endif
 
 #define WARN_ON_ONCE(condition)        ({                              \
-       static bool __warned;                                   \
+       static bool __section(.data.unlikely) __warned;         \
        int __ret_warn_once = !!(condition);                    \
                                                                \
        if (unlikely(__ret_warn_once))                          \
@@ -144,7 +144,7 @@ extern void warn_slowpath_null(const char *file, const int line);
 })
 
 #define WARN_ONCE(condition, format...)        ({                      \
-       static bool __warned;                                   \
+       static bool __section(.data.unlikely) __warned;         \
        int __ret_warn_once = !!(condition);                    \
                                                                \
        if (unlikely(__ret_warn_once))                          \
@@ -154,7 +154,7 @@ extern void warn_slowpath_null(const char *file, const int line);
 })
 
 #define WARN_TAINT_ONCE(condition, taint, format...)   ({      \
-       static bool __warned;                                   \
+       static bool __section(.data.unlikely) __warned;         \
        int __ret_warn_once = !!(condition);                    \
                                                                \
        if (unlikely(__ret_warn_once))                          \
index b5e2e4c..798603e 100644 (file)
        CPU_KEEP(exit.data)                                             \
        MEM_KEEP(init.data)                                             \
        MEM_KEEP(exit.data)                                             \
+       *(.data.unlikely)                                               \
        STRUCT_ALIGN();                                                 \
        *(__tracepoints)                                                \
        /* implement dynamic printk debug */                            \
index 9372174..2c62594 100644 (file)
@@ -418,7 +418,7 @@ extern int rcu_my_thread_group_empty(void);
  */
 #define rcu_lockdep_assert(c, s)                                       \
        do {                                                            \
-               static bool __warned;                                   \
+               static bool __section(.data.unlikely) __warned;         \
                if (debug_lockdep_rcu_enabled() && !__warned && !(c)) { \
                        __warned = true;                                \
                        lockdep_rcu_suspicious(__FILE__, __LINE__, s);  \