Commit 197165d4 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

powerpc/ftrace: add powerpc timebase as a trace clock source 



Add a new powerpc-specific trace clock using the timebase register,
similar to x86-tsc. This gives us
- a fast, monotonic, hardware clock source for trace entries, and
- a clock that can be used to correlate events across cpus as well as across
  hypervisor and guests.

Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 35a7f41c

Documentation/trace/ftrace.txt

+5 −0
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@@ -346,6 +346,11 @@ of ftrace. Here is a list of some of the key files: 
	  x86-tsc: Architectures may define their own clocks. For

	  	   example, x86 uses its own TSC cycle clock here.



	  ppc-tb: This uses the powerpc timebase register value.

		  This is in sync across CPUs and can also be used

		  to correlate events across hypervisor/guest if

		  tb_offset is known.



	To set a clock, simply echo the clock name into this file.



	  echo global > trace_clock

arch/powerpc/include/asm/Kbuild

+0 −1
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@@ -6,5 +6,4 @@ generic-y += local64.h 
generic-y += mcs_spinlock.h

generic-y += preempt.h

generic-y += rwsem.h

generic-y += trace_clock.h

generic-y += vtime.h

arch/powerpc/include/asm/trace_clock.h

0 → 100644
+19 −0
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/*

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License, version 2, as

 * published by the Free Software Foundation.

 *

 * Copyright (C) 2015 Naveen N. Rao, IBM Corporation

 */



#ifndef _ASM_PPC_TRACE_CLOCK_H

#define _ASM_PPC_TRACE_CLOCK_H



#include <linux/compiler.h>

#include <linux/types.h>



extern u64 notrace trace_clock_ppc_tb(void);



#define ARCH_TRACE_CLOCKS { trace_clock_ppc_tb, "ppc-tb", 0 },



#endif  /* _ASM_PPC_TRACE_CLOCK_H */

arch/powerpc/kernel/Makefile

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@@ -118,6 +118,7 @@ obj-$(CONFIG_PPC_IO_WORKAROUNDS) += io-workarounds.o 
obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o

obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o

obj-$(CONFIG_TRACING)		+= trace_clock.o



ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)

obj-y				+= iomap.o

arch/powerpc/kernel/trace_clock.c

0 → 100644
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/*

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License, version 2, as

 * published by the Free Software Foundation.

 *

 * Copyright (C) 2015 Naveen N. Rao, IBM Corporation

 */



#include <asm/trace_clock.h>

#include <asm/time.h>



u64 notrace trace_clock_ppc_tb(void)

{

	return get_tb();

}

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