[PATCH] ARM: Stop irqsoff trace on return to user

[PATCH] ARM: Stop irqsoff trace on return to user

[Todd Poynor]

If the irqsoff tracer is in use, stop tracing the interrupt disable
interval when returning to userspace.  Tracing userspace execution
time as interrupts disabled time is not helpful for kernel
performance analysis purposes.  Only do so if the irqsoff tracer
is enabled, to avoid overhead purely for lockdep, which doesn't
care.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 arch/arm/kernel/entry-common.S |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 8bfa987..80bf8cd 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -29,6 +29,9 @@ ret_fast_syscall:
 	ldr	r1, [tsk, #TI_FLAGS]
 	tst	r1, #_TIF_WORK_MASK
 	bne	fast_work_pending
+#if defined(CONFIG_IRQSOFF_TRACER)
+	asm_trace_hardirqs_on
+#endif
 
 	/* perform architecture specific actions before user return */
 	arch_ret_to_user r1, lr
@@ -65,6 +68,9 @@ ret_slow_syscall:
 	tst	r1, #_TIF_WORK_MASK
 	bne	work_pending
 no_work_pending:
+#if defined(CONFIG_IRQSOFF_TRACER)
+	asm_trace_hardirqs_on
+#endif
 	/* perform architecture specific actions before user return */
 	arch_ret_to_user r1, lr
 
-- 
1.7.3.1

[PATCH] ARM: Stop irqsoff trace on return to user

[Todd Poynor]

If the irqsoff tracer is in use, stop tracing the interrupt disable
interval when returning to userspace.  Tracing userspace execution
time as interrupts disabled time is not useful for kernel
performance analysis purposes, and crowds out more helpful results
with long userspace execution times.  Some other architectures do
something similar.

Only do so if the irqsoff tracer is enabled, to avoid overhead for
lockdep, which doesn't care about userspace execution time with
interrupts disabled.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 arch/arm/kernel/entry-common.S |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 8bfa987..80bf8cd 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -29,6 +29,9 @@ ret_fast_syscall:
 	ldr	r1, [tsk, #TI_FLAGS]
 	tst	r1, #_TIF_WORK_MASK
 	bne	fast_work_pending
+#if defined(CONFIG_IRQSOFF_TRACER)
+	asm_trace_hardirqs_on
+#endif
 
 	/* perform architecture specific actions before user return */
 	arch_ret_to_user r1, lr
@@ -65,6 +68,9 @@ ret_slow_syscall:
 	tst	r1, #_TIF_WORK_MASK
 	bne	work_pending
 no_work_pending:
+#if defined(CONFIG_IRQSOFF_TRACER)
+	asm_trace_hardirqs_on
+#endif
 	/* perform architecture specific actions before user return */
 	arch_ret_to_user r1, lr
 
-- 
1.7.3.1

[PATCH] ARM: Stop irqsoff trace on return to user

[Russell King - ARM Linux]

On Fri, Dec 03, 2010 at 07:41:47PM -0800, Todd Poynor wrote:
> If the irqsoff tracer is in use, stop tracing the interrupt disable
> interval when returning to userspace.  Tracing userspace execution
> time as interrupts disabled time is not useful for kernel
> performance analysis purposes, and crowds out more helpful results
> with long userspace execution times.  Some other architectures do
> something similar.
> 
> Only do so if the irqsoff tracer is enabled, to avoid overhead for
> lockdep, which doesn't care about userspace execution time with
> interrupts disabled.

Ok, can you send this to the patch system please?