From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Chris Metcalf <cmetcalf@mellanox.com>,
Thomas Gleixner <tglx@linutronix.de>,
Christoph Lameter <cl@linux.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Wanpeng Li <kernellwp@gmail.com>, Mike Galbraith <efault@gmx.de>,
Rik van Riel <riel@redhat.com>
Subject: Re: [GIT PULL] isolation: 1Hz residual tick offloading v4
Date: Mon, 29 Jan 2018 16:47:40 +0100 [thread overview]
Message-ID: <20180129154740.GV2269@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180129011024.GA2942@lerouge>
On Mon, Jan 29, 2018 at 02:10:26AM +0100, Frederic Weisbecker wrote:
> It's beyond the scope of this patchset but indeed that's right, I run my
> kernels with tsc=reliable because my CPUs don't have the TSC_RELIABLE flag.
> That's the only way I found to shutdown the tick completely on my test
> machine, otherwise I keep having that clocksource watchdog.
>
> You can try "tsc=reliable" but that's at your own risks and it's hard
> to tell what exactly are those risks depending on your CPU model (and
> perhaps BIOS?).
BIOS, anything Nehalem and later, BIOS monkeys are to blame. There is
one exception to that, and that is very large socket count machines, and
these people typically already know what they got themselves into.
If your machine never triggers the watchdog with your workload, booting
with tsc=reliable is safe (for that workload).
But if you trip the watchdog, booting with tsc=reliable is a very bad
idea indeed.
next prev parent reply other threads:[~2018-01-29 15:47 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-19 0:02 Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 1/6] sched: Rename init_rq_hrtick to hrtick_rq_init Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 2/6] nohz: Allow to check if remote CPU tick is stopped Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 3/6] sched/isolation: Isolate workqueues when "nohz_full=" is set Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 4/6] sched/isolation: Residual 1Hz scheduler tick offload Frederic Weisbecker
2018-01-29 15:38 ` Peter Zijlstra
2018-01-29 16:48 ` Frederic Weisbecker
2018-01-29 17:20 ` Peter Zijlstra
2018-01-29 15:39 ` Peter Zijlstra
2018-01-19 0:02 ` [PATCH 5/6] sched/nohz: Remove the 1 Hz tick code Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 6/6] sched/isolation: Tick offload documentation Frederic Weisbecker
2018-01-24 15:46 ` [GIT PULL] isolation: 1Hz residual tick offloading v4 Luiz Capitulino
2018-01-29 1:10 ` Frederic Weisbecker
2018-01-29 15:33 ` Luiz Capitulino
2018-01-29 15:54 ` Peter Zijlstra
2018-01-29 16:27 ` Luiz Capitulino
2018-01-29 15:47 ` Peter Zijlstra [this message]
2018-05-22 19:10 ` Yauheni Kaliuta
2018-05-25 2:56 ` Frederic Weisbecker
2018-05-25 12:51 ` Luiz Capitulino
2018-01-29 1:18 ` (Ping?) " Frederic Weisbecker
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