* [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer
@ 2009-03-22 17:01 Frederic Weisbecker
2009-03-22 17:03 ` Ingo Molnar
2009-03-23 18:46 ` Steven Rostedt
0 siblings, 2 replies; 3+ messages in thread
From: Frederic Weisbecker @ 2009-03-22 17:01 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Steven Rostedt, LKML, Frederic Weisbecker
Impact: fix slow tracing
The core kernel tracing is protected against soft branch profiling, but
not the x86 ftrace arch part. Let's fix it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
arch/x86/kernel/Makefile | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 599e9a7..8d9b3f9 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -13,6 +13,7 @@ CFLAGS_REMOVE_rtc.o = -pg
CFLAGS_REMOVE_paravirt-spinlocks.o = -pg
CFLAGS_REMOVE_ftrace.o = -pg
CFLAGS_REMOVE_early_printk.o = -pg
+CFLAGS_ftrace.o += -DDISABLE_BRANCH_PROFILING
endif
#
--
1.6.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer
2009-03-22 17:01 [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer Frederic Weisbecker
@ 2009-03-22 17:03 ` Ingo Molnar
2009-03-23 18:46 ` Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Ingo Molnar @ 2009-03-22 17:03 UTC (permalink / raw)
To: Frederic Weisbecker; +Cc: Steven Rostedt, LKML
* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> Impact: fix slow tracing
>
> The core kernel tracing is protected against soft branch
> profiling, but not the x86 ftrace arch part. Let's fix it.
right now we should simply disable the branch profiler if any
function tracing variant is enabled.
We should probably mark it CONFIG_BROKEN until it's properly
per-cpu-ized.
Ingo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer
2009-03-22 17:01 [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer Frederic Weisbecker
2009-03-22 17:03 ` Ingo Molnar
@ 2009-03-23 18:46 ` Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Steven Rostedt @ 2009-03-23 18:46 UTC (permalink / raw)
To: Frederic Weisbecker; +Cc: Ingo Molnar, LKML
On Sun, 22 Mar 2009, Frederic Weisbecker wrote:
> Impact: fix slow tracing
>
> The core kernel tracing is protected against soft branch profiling, but
> not the x86 ftrace arch part. Let's fix it.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> arch/x86/kernel/Makefile | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 599e9a7..8d9b3f9 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -13,6 +13,7 @@ CFLAGS_REMOVE_rtc.o = -pg
> CFLAGS_REMOVE_paravirt-spinlocks.o = -pg
> CFLAGS_REMOVE_ftrace.o = -pg
> CFLAGS_REMOVE_early_printk.o = -pg
> +CFLAGS_ftrace.o += -DDISABLE_BRANCH_PROFILING
> endif
>
Actually, I prefer not to do this. I do use the branch profiling on
ftrace, to see where the hot paths are.
-- Steve
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2009-03-23 18:46 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2009-03-22 17:01 [PATCH] tracing/function-graph-tracer: don't profile branches on graph tracer Frederic Weisbecker
2009-03-22 17:03 ` Ingo Molnar
2009-03-23 18:46 ` Steven Rostedt
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