[PATCH] s390: external call performance
The kernel uses the SIGP external call order code to signal other CPUs. When
running with dedicated CPUs external calls don't get delivered immediately but
within a fixed polling invervall. This can lead to delays where the system
appears to do nothing. Replace the SIGP external call order with the SIGP
emergency call order since this one gets delivered immediately.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index fc8bf5e..928ca65 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -765,7 +765,7 @@
# check control registers
stctl %c0,%c15,0(%r15)
- oi 2(%r15),0x20 # enable sigp external interrupts
+ oi 2(%r15),0x40 # enable sigp emergency signal
oi 0(%r15),0x10 # switch on low address protection
lctl %c0,%c15,0(%r15)