From: Hans-Joachim Picht <hpicht@redhat.com>
Date: Thu, 3 Apr 2008 15:41:25 +0200
Subject: [s390] zcrypt: disable ap polling thread per default
Message-id: 20080403134125.GI10542@redhat.com
O-Subject: [RHEL5 U3 PATCH 7/7] s390 - zcrypt: Disable ap polling thread per default
Bugzilla: 435161
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

Description
============

The AP polling thread which is enabled by default will cause a high cpu cost with z/VM.
z/VMs polling rate is much lower then the ap poll thread in Linux for System z.

This patch disables the ap polling thread per default.

Bugzilla
=========

BZ 435161
https://bugzilla.redhat.com/show_bug.cgi?id=435161

Upstream status of the patch:
=============================

Patch included in linux-2.6 as git commit
b90b34c6802865d07f482650eff82a4b38df6d79

Test status:
============
Kernel with patch was built and successfully tested

Please ACK.

With best regards,

Hans

 drivers/s390/crypto/ap_bus.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 2f9c250..73efe9e 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -59,9 +59,9 @@ module_param_named(domain, ap_domain_index, int, 0000);
 MODULE_PARM_DESC(domain, "domain index for ap devices");
 EXPORT_SYMBOL(ap_domain_index);
 
-static int ap_thread_flag = 1;
+static int ap_thread_flag = 0;
 module_param_named(poll_thread, ap_thread_flag, int, 0000);
-MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 1 (on).");
+MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 0 (off).");
 
 static struct device *ap_root_device = NULL;