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From: Peter Zijlstra <peterz@infradead.org>
To: Martin Peres <martin.peres@linux.intel.com>
Cc: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"pasha.tatashin@oracle.com" <pasha.tatashin@oracle.com>
Subject: Re: freedesktop bug id: 100548, bisected to sched/clock commit
Date: Thu, 13 Apr 2017 13:48:03 +0200	[thread overview]
Message-ID: <20170413114803.poziwglvrzbmtmvb@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <8b94e683-3d09-d5dc-cfd1-746f179f3678@linux.intel.com>

On Wed, Apr 12, 2017 at 05:49:53PM +0300, Martin Peres wrote:

> Good to know. Is there a way to disable this behaviour, as a workaround for
> our CI system until a proper fix lands? We already pushed locally the revert
> for this patch, but that may affect other platforms which do not exhibit the
> problem.

Blergh, so the patch is correct, but the __gtod_offset calculation is
fed with absolute crap numbers due to 'circumstances' and then using it
ends up being worse than not using it.

Something like the below could be a work-around, but let me see if I
can't fix things better.

---
 arch/x86/kernel/tsc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 714dfba..8ab883a 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -374,6 +374,8 @@ static int __init tsc_setup(char *str)
 		tsc_clocksource_reliable = 1;
 	if (!strncmp(str, "noirqtime", 9))
 		no_sched_irq_time = 1;
+	if (!strcmp(str, "unstable"))
+		mark_tsc_unstable("boot parameter");
 	return 1;
 }
 
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  parent reply	other threads:[~2017-04-13 11:48 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-12 12:04 freedesktop bug id: 100548, bisected to sched/clock commit Lofstedt, Marta
2017-04-12 12:31 ` Peter Zijlstra
2017-04-12 13:30   ` Jani Nikula
2017-04-12 14:28     ` Peter Zijlstra
2017-04-12 13:40   ` Martin Peres
2017-04-12 14:32     ` Peter Zijlstra
2017-04-12 14:49       ` Martin Peres
2017-04-12 15:50         ` Peter Zijlstra
2017-04-13 11:48         ` Peter Zijlstra [this message]
2017-04-13 12:30           ` Martin Peres
2017-04-13 13:23             ` Peter Zijlstra
2017-04-13 14:55               ` Thomas Gleixner
2017-04-18 14:10               ` Lofstedt, Marta
2017-04-18 15:53                 ` Peter Zijlstra
2017-04-20 17:19                   ` Peter Zijlstra
2017-04-20 19:36                     ` Peter Zijlstra

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