From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Fri, 14 Nov 2008 17:18:04 +0000 (+0100)
Subject: [S390] ftrace: disable tracing on idle psw
X-Git-Tag: v2.6.28-rc5~8^2~5
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=632448f65001c4935ed0d3bb362017d773da2eca;p=linux-2.6-omap-h63xx.git

[S390] ftrace: disable tracing on idle psw

Disable tracing on idle psw. Otherwise it would give us huge
preempt off times for idle. Which is rather pointless.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 3e2c05cb6a8..04f8c67a610 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -136,9 +136,12 @@ static void default_idle(void)
 		return;
 	}
 	trace_hardirqs_on();
+	/* Don't trace preempt off for idle. */
+	stop_critical_timings();
 	/* Wait for external, I/O or machine check interrupt. */
 	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 			PSW_MASK_IO | PSW_MASK_EXT);
+	start_critical_timings();
 }
 
 void cpu_idle(void)