x86, sched_clock(): mark variables read-mostly

Impact: micro-optimization There's a number of variables in the sched_clock() path that are in .data/.bss - but not marked __read_mostly. This creates the danger of accidental false cacheline sharing with some other, write-often variable. So mark them __read_mostly. Signed-off-by: Ingo Molnar <[email protected]>
mna · Mar 10, 2009 · f24ade3 · f24ade3
1 parent 8325d9c
commit f24ade3
Showing 1 changed file with 5 additions and 4 deletions.
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
@@ -17,20 +17,21 @@
 #include <asm/delay.h>
 #include <asm/hypervisor.h>
 
-unsigned int cpu_khz;           /* TSC clocks / usec, not used here */
+unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
-unsigned int tsc_khz;
+
+unsigned int __read_mostly tsc_khz;
 EXPORT_SYMBOL(tsc_khz);
 
 /*
  * TSC can be unstable due to cpufreq or due to unsynced TSCs
  */
-static int tsc_unstable;
+static int __read_mostly tsc_unstable;
 
 /* native_sched_clock() is called before tsc_init(), so
    we must start with the TSC soft disabled to prevent
    erroneous rdtsc usage on !cpu_has_tsc processors */
-static int tsc_disabled = -1;
+static int __read_mostly tsc_disabled = -1;
 
 static int tsc_clocksource_reliable;
 /*