Re: [PATCH] powerpc/ftrace: add powerpc timebase as a trace clock source
On 2015/04/23 09:10AM, Steven Rostedt wrote: > On Thu, 23 Apr 2015 12:15:04 +0530 > "Naveen N. Rao" wrote: > > > diff --git a/arch/powerpc/include/asm/trace_clock.h > > b/arch/powerpc/include/asm/trace_clock.h > > new file mode 100644 > > index 000..0b0d094 > > --- /dev/null > > +++ b/arch/powerpc/include/asm/trace_clock.h > > @@ -0,0 +1,27 @@ > > +/* > > + * 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 > > +#include > > + > > +#ifdef CONFIG_TRACE_CLOCK > > You don't need this #if statement. What else is using this besides > kernel/trace/trace.c, which selects TRACE_CLOCK if it is compiled. > > If you were trying to match x86, where it has: > > #ifdef CONFIG_X86_TSC > > where you have CONFIG_TRACE_CLOCK. We needed the #ifdef because you > can compile the x86 kernel without TSC support, and we did not want to > export a tsc tracing clock if one did not exist. > > And the only place that I see that even includes this header in ppc, is > also only compiled if CONFIG_TRACE_CLOCK is selected. Ah yes, agreed. I have removed it and seeing as CONFIG_TRACE_CLOCK is really for the generic clocks, I have moved the dependency on arch/powerpc/kernel/trace_clock.o to CONFIG_TRACING since that is what gates kernel/trace/trace.o > > I'm fine with the change, just nuke the unnecessary #ifdef. Thanks for the review! - Naveen ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] powerpc/ftrace: add powerpc timebase as a trace clock source
On Thu, 23 Apr 2015 12:15:04 +0530
"Naveen N. Rao" wrote:
> diff --git a/arch/powerpc/include/asm/trace_clock.h
> b/arch/powerpc/include/asm/trace_clock.h
> new file mode 100644
> index 000..0b0d094
> --- /dev/null
> +++ b/arch/powerpc/include/asm/trace_clock.h
> @@ -0,0 +1,27 @@
> +/*
> + * 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
> +#include
> +
> +#ifdef CONFIG_TRACE_CLOCK
You don't need this #if statement. What else is using this besides
kernel/trace/trace.c, which selects TRACE_CLOCK if it is compiled.
If you were trying to match x86, where it has:
#ifdef CONFIG_X86_TSC
where you have CONFIG_TRACE_CLOCK. We needed the #ifdef because you
can compile the x86 kernel without TSC support, and we did not want to
export a tsc tracing clock if one did not exist.
And the only place that I see that even includes this header in ppc, is
also only compiled if CONFIG_TRACE_CLOCK is selected.
I'm fine with the change, just nuke the unnecessary #ifdef.
-- Steve
> +
> +extern u64 notrace trace_clock_ppc_tb(void);
> +
> +#define ARCH_TRACE_CLOCKS { trace_clock_ppc_tb, "ppc-tb", 0 },
> +
> +#else
> +
> +#define ARCH_TRACE_CLOCKS
> +
> +#endif /* CONFIG_TRACE_CLOCK */
> +
> +#endif /* _ASM_PPC_TRACE_CLOCK_H */
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 502cf69..f9936f3 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -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-$(CONFIG_TRACE_CLOCK)+= trace_clock.o
>
> ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)
> obj-y+= iomap.o
> diff --git a/arch/powerpc/kernel/trace_clock.c
> b/arch/powerpc/kernel/trace_clock.c
> new file mode 100644
> index 000..4917069
> --- /dev/null
> +++ b/arch/powerpc/kernel/trace_clock.c
> @@ -0,0 +1,15 @@
> +/*
> + * 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
> +#include
> +
> +u64 notrace trace_clock_ppc_tb(void)
> +{
> + return get_tb();
> +}
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[PATCH] 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: Naveen N. Rao
---
Changes since RFC: Updated description.
Previous discussion:
http://thread.gmane.org/gmane.linux.ports.ppc.embedded/80409
Steve,
Can you please provide your ack for this?
Thanks,
Naveen
Documentation/trace/ftrace.txt | 5 +
arch/powerpc/include/asm/Kbuild| 1 -
arch/powerpc/include/asm/trace_clock.h | 27 +++
arch/powerpc/kernel/Makefile | 1 +
arch/powerpc/kernel/trace_clock.c | 15 +++
5 files changed, 48 insertions(+), 1 deletion(-)
create mode 100644 arch/powerpc/include/asm/trace_clock.h
create mode 100644 arch/powerpc/kernel/trace_clock.c
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 572ca92..689f61a 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -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
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index 382b28e..5041c66 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -5,5 +5,4 @@ generic-y += mcs_spinlock.h
generic-y += preempt.h
generic-y += rwsem.h
generic-y += scatterlist.h
-generic-y += trace_clock.h
generic-y += vtime.h
diff --git a/arch/powerpc/include/asm/trace_clock.h
b/arch/powerpc/include/asm/trace_clock.h
new file mode 100644
index 000..0b0d094
--- /dev/null
+++ b/arch/powerpc/include/asm/trace_clock.h
@@ -0,0 +1,27 @@
+/*
+ * 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
+#include
+
+#ifdef CONFIG_TRACE_CLOCK
+
+extern u64 notrace trace_clock_ppc_tb(void);
+
+#define ARCH_TRACE_CLOCKS { trace_clock_ppc_tb, "ppc-tb", 0 },
+
+#else
+
+#define ARCH_TRACE_CLOCKS
+
+#endif /* CONFIG_TRACE_CLOCK */
+
+#endif /* _ASM_PPC_TRACE_CLOCK_H */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 502cf69..f9936f3 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -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-$(CONFIG_TRACE_CLOCK) += trace_clock.o
ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)
obj-y += iomap.o
diff --git a/arch/powerpc/kernel/trace_clock.c
b/arch/powerpc/kernel/trace_clock.c
new file mode 100644
index 000..4917069
--- /dev/null
+++ b/arch/powerpc/kernel/trace_clock.c
@@ -0,0 +1,15 @@
+/*
+ * 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
+#include
+
+u64 notrace trace_clock_ppc_tb(void)
+{
+ return get_tb();
+}
--
2.3.5
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