[patch 1/7] clocksource: Restructure clocksource struct members
From: Thomas Gleixner
Date: Wed May 18 2011 - 17:34:29 EST
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@xxxxxxxxxxxxx>
Eric Dumazet <eric.dumazet@xxxxxxxxx>
---
include/linux/clocksource.h | 32 ++++++++++++++------------------
1 file changed, 14 insertions(+), 18 deletions(-)
Index: linux-2.6-tip/include/linux/clocksource.h
===================================================================
--- linux-2.6-tip.orig/include/linux/clocksource.h
+++ linux-2.6-tip/include/linux/clocksource.h
@@ -159,42 +159,38 @@ extern u64 timecounter_cyc2time(struct t
*/
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::
--
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