linux-kernel - [patch] i386, numaq: enable TSCs again

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Message-ID: <20070525080827.GA22399@elte.hu>
Date:	Fri, 25 May 2007 10:08:27 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Satyam Sharma <satyam.sharma@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [patch] i386, numaq: enable TSCs again


Andi, Andrew, do you remember why we disabled TSCs on NUMAQ? It was 
slightly async between CPUs, right? In that case we should try the patch 
below.

	Ingo

--------------------->
Subject: [patch] i386, numaq: enable TSCs again
From: Ingo Molnar <mingo@...e.hu>

enable TSCs on NUMAQ again. sched_clock() got improved and
the scheduler treats it as a per-CPU clock, so there should
be no issues from the slightly async TSCs on NUMAQ. Please
holler if this is wrong ...

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/i386/kernel/numaq.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Index: linux-cfs-2.6.22-rc2-mm1.q/arch/i386/kernel/numaq.c
===================================================================
--- linux-cfs-2.6.22-rc2-mm1.q.orig/arch/i386/kernel/numaq.c
+++ linux-cfs-2.6.22-rc2-mm1.q/arch/i386/kernel/numaq.c
@@ -81,8 +81,7 @@ int __init get_memcfg_numaq(void)
 static int __init numaq_tsc_disable(void)
 {
 	if (num_online_nodes() > 1) {
-		printk(KERN_DEBUG "NUMAQ: disabling TSC\n");
-		tsc_disable = 1;
+		printk(KERN_DEBUG "NUMAQ: NOT disabling TSC. System still ok?\n");
 	}
 	return 0;
 }

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