clocksource: Restructure clocksource struct members

Group the hot path members of struct clocksource together so we have a
better cache line footprint. Make it cacheline aligned.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/%3C20110518210136.003081882%40linutronix.de%3E

1 files changed, 14 insertions, 18 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 0fb0b7e79394..c918fbd33ee5 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -159,42 +159,38 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
  */
 struct clocksource {
         /*
-         * First part of structure is read mostly
+         * Hotpath data, fits in a single cache line when the
+         * clocksource itself is cacheline aligned.
          */
-        const char *name;
-        struct list_head list;
-        int rating;
         cycle_t (*read)(struct clocksource *cs);
-        int (*enable)(struct clocksource *cs);
-        void (*disable)(struct clocksource *cs);
+        cycle_t cycle_last;
         cycle_t mask;
         u32 mult;
         u32 shift;
         u64 max_idle_ns;
-        unsigned long flags;
-        cycle_t (*vread)(void);
-        void (*suspend)(struct clocksource *cs);
-        void (*resume)(struct clocksource *cs);
+
 #ifdef CONFIG_IA64
         void *fsys_mmio;        /* used by fsyscall asm code */
 #define CLKSRC_FSYS_MMIO_SET(mmio, addr)      ((mmio) = (addr))
 #else
 #define CLKSRC_FSYS_MMIO_SET(mmio, addr)      do { } while (0)
 #endif
-
-        /*
-         * Second part is written at each timer interrupt
-         * Keep it in a different cache line to dirty no
-         * more than one cache line.
-         */
-        cycle_t cycle_last ____cacheline_aligned_in_smp;
+        const char *name;
+        struct list_head list;
+        int rating;
+        cycle_t (*vread)(void);
+        int (*enable)(struct clocksource *cs);
+        void (*disable)(struct clocksource *cs);
+        unsigned long flags;
+        void (*suspend)(struct clocksource *cs);
+        void (*resume)(struct clocksource *cs);
 
 #ifdef CONFIG_CLOCKSOURCE_WATCHDOG
         /* Watchdog related data, used by the framework */
         struct list_head wd_list;
         cycle_t wd_last;
 #endif
-};
+} ____cacheline_aligned;
 
 /*
  * Clock source flags bits::