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x86, sched_clock(): mark variables read-mostly

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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 <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-03-10 19:02:30 +01:00
parent 8325d9c09d
commit f24ade3a33
1 changed files with 5 additions and 4 deletions
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9
arch/x86/kernel/tsc.c
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@ -17,20 +17,21 @@
#include <asm/delay.h> #include <asm/delay.h>
#include <asm/hypervisor.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); EXPORT_SYMBOL(cpu_khz);
unsigned int tsc_khz;
unsigned int __read_mostly tsc_khz;
EXPORT_SYMBOL(tsc_khz); EXPORT_SYMBOL(tsc_khz);
/* /*
* TSC can be unstable due to cpufreq or due to unsynced TSCs * 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 /* native_sched_clock() is called before tsc_init(), so
we must start with the TSC soft disabled to prevent we must start with the TSC soft disabled to prevent
erroneous rdtsc usage on !cpu_has_tsc processors */ 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; static int tsc_clocksource_reliable;
/* /*