RE: Latency traces I cannot interpret (sa1100, 2.6.15-rc7-rt1)

[Daniel Walker]

Here's a more updated patch, the should replace the other patch I sent.
I think the tracing error is the result of a missed interrupt enable in
the ARM assembly code. I've only compile tested this.  

Daniel

On Mon, 2006-01-02 at 15:55 +0100, kus Kusche Klaus wrote:
> > From: Daniel Walker
> > Right .. I'm still looking into it. ARM is just missing some vital
> > tracing bits I think .
> 
> As I wrote in some earlier mail, I'm probably the first one ever
> who tried it on ARM: When I tried first, tracing didn't work at all,
> because the trace timing macro's were not defined (at least for
> sa1100). I quick-hacked the three missing macros (this caused the
> tracer to produce at least some output) without checking if 
> anything else is missing.
> 
> 
Index: linux-2.6.14/arch/arm/kernel/process.c
===================================================================
--- linux-2.6.14.orig/arch/arm/kernel/process.c
+++ linux-2.6.14/arch/arm/kernel/process.c
@@ -89,12 +89,12 @@ void default_idle(void)
 	if (hlt_counter)
 		cpu_relax();
 	else {
-		raw_local_irq_disable();
+		__raw_local_irq_disable();
 		if (!need_resched()) {
 			timer_dyn_reprogram();
 			arch_idle();
 		}
-		raw_local_irq_enable();
+		__raw_local_irq_enable();
 	}
 }
 
@@ -121,8 +121,10 @@ void cpu_idle(void)
 		if (!idle)
 			idle = default_idle;
 		leds_event(led_idle_start);
+		__preempt_enable_no_resched();
 		while (!need_resched())
 			idle();
+		preempt_disable();
 		leds_event(led_idle_end);
 		__preempt_enable_no_resched();
 		__schedule();
Index: linux-2.6.14/arch/arm/kernel/entry-header.S
===================================================================
--- linux-2.6.14.orig/arch/arm/kernel/entry-header.S
+++ linux-2.6.14/arch/arm/kernel/entry-header.S
@@ -38,18 +38,30 @@
 
 #if __LINUX_ARM_ARCH__ >= 6
 	.macro	disable_irq
+#ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
+	b	trace_irqs_off
+#endif
 	cpsid	i
 	.endm
 
 	.macro	enable_irq
+#ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
+	b	trace_irqs_on
+#endif
 	cpsie	i
 	.endm
 #else
 	.macro	disable_irq
+#ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
+	b	trace_irqs_off
+#endif
 	msr	cpsr_c, #PSR_I_BIT | SVC_MODE
 	.endm
 
 	.macro	enable_irq
+#ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
+	b	trace_irqs_on
+#endif
 	msr	cpsr_c, #SVC_MODE
 	.endm
 #endif