[Lucid-ec2] SRU: XEN: Do not force sched_clock_stable

Stefan Bader stefan.bader at canonical.com
Tue May 17 17:29:34 UTC 2011


SRU Justification

Impact: When applying the Xen patchset one endif seems to have gone to
the wrong place. So instead of not setting sched_clock_stable it is done
all the time.

Fix: Move endif so the whole code segment is covered.

Testcase: Can cause various effects and depends on CPU (see below).
Incorrect CPU time but likely also causing the unexplainable process
gets stuck or clone/fork issues.

---

>From 5f1bda076198807960d023c4d1551485c8d77ef5 Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader at canonical.com>
Date: Tue, 17 May 2011 19:16:30 +0200
Subject: [PATCH] UBUNTU: SAUCE: XEN: Do not force sched_clock_stable

BugLink: http://bugs.launchpad.net/bugs/727459

This is part of the changes that have been found while syncing up
the patchsets. Apparently when applying the endif went into the
wrong place and causes the clock to be assumed always stable. Which
causes problems on certain CPUs (probably the fork/clone hang as well
as processes getting stuck for a longer time).

Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 arch/x86/kernel/cpu/intel.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 0aad121..f582b21 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -97,8 +97,8 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
 		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
 #ifndef CONFIG_XEN
 		if (!check_tsc_unstable())
-#endif
 			sched_clock_stable = 1;
+#endif
 	}
 
 	/*
-- 
1.7.0.4





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