| Message ID | 1429771504-32688-1-git-send-email-naveen.n.rao@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Michael Ellerman |
| Headers | show |
On Thu, 23 Apr 2015 12:15:04 +0530 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote: > diff --git a/arch/powerpc/include/asm/trace_clock.h b/arch/powerpc/include/asm/trace_clock.h > new file mode 100644 > index 0000000..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 <linux/compiler.h> > +#include <linux/types.h> > + > +#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 0000000..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 <asm/trace_clock.h> > +#include <asm/time.h> > + > +u64 notrace trace_clock_ppc_tb(void) > +{ > + return get_tb(); > +}
On 2015/04/23 09:10AM, Steven Rostedt wrote: > On Thu, 23 Apr 2015 12:15:04 +0530 > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote: > > > diff --git a/arch/powerpc/include/asm/trace_clock.h b/arch/powerpc/include/asm/trace_clock.h > > new file mode 100644 > > index 0000000..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 <linux/compiler.h> > > +#include <linux/types.h> > > + > > +#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
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 0000000..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 <linux/compiler.h> +#include <linux/types.h> + +#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 0000000..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 <asm/trace_clock.h> +#include <asm/time.h> + +u64 notrace trace_clock_ppc_tb(void) +{ + return get_tb(); +}
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 <naveen.n.rao@linux.vnet.ibm.com> --- 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