Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c8e5910e authored by Robert Richter's avatar Robert Richter Committed by Ingo Molnar
Browse files

perf, x86: Use ALTERNATIVE() to check for X86_FEATURE_PERFCTR_CORE 



Using ALTERNATIVE() when checking for X86_FEATURE_PERFCTR_CORE avoids
an extra pointer chase and data cache hit.

Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1302913676-14352-4-git-send-email-robert.richter@amd.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 68d2cf25

arch/x86/kernel/cpu/perf_event.c

+11 −4
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <asm/nmi.h>

#include <asm/compat.h>

#include <asm/smp.h>

#include <asm/alternative.h>



#if 0

#undef wrmsrl
@@ -363,12 +364,18 @@ x86_perf_event_update(struct perf_event *event) 
	return new_raw_count;

}



/* using X86_FEATURE_PERFCTR_CORE to later implement ALTERNATIVE() here */

static inline int x86_pmu_addr_offset(int index)

{

	if (boot_cpu_has(X86_FEATURE_PERFCTR_CORE))

		return index << 1;

	return index;

	int offset;



	/* offset = X86_FEATURE_PERFCTR_CORE ? index << 1 : index */

	alternative_io(ASM_NOP2,

		       "shll $1, %%eax",

		       X86_FEATURE_PERFCTR_CORE,

		       "=a" (offset),

		       "a"  (index));



	return offset;

}



static inline unsigned int x86_pmu_config_addr(int index)