From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Suleiman Souhlal <suleiman@google.com>,
rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu/tree: consider time a VM was suspended
Date: Fri, 21 May 2021 07:34:41 +0900 [thread overview]
Message-ID: <YKbkAXELPxXJcsHA@google.com> (raw)
In-Reply-To: <20210520145708.GK4441@paulmck-ThinkPad-P17-Gen-1>
On (21/05/20 07:57), Paul E. McKenney wrote:
> >
> > Sounds good. I can cook a patch and run some tests.
> > Or do you want to send a patch?
>
> Given that you have the test setup, things might go faster if you do
> the patch, especially taking timezones into consideration. Of course,
> if you run into difficulties, you know where to find me.
OK. Sounds good to me.
> > While VCPU-2 has PVCLOCK_GUEST_STOPPED set (resuming) and is in
> > check_cpu_stall(), the VCPU-3 is executing:
> >
> > apic_timer_interrupt()
> > tick_irq_enter()
> > tick_do_update_jiffies64()
> > do_timer()
>
> OK, but the normal grace period time is way less than one second, and
> the stall timeout in mainline is 21 seconds, so that would be a -lot-
> of jiffies of skew. Or does the restarting really take that long a time?
That's a good question. I see huge jiffies spike in the logs.
I suspect that resuming a VM can take some time, especially on a "not
powerful at all" overcommitted host (more virtual CPUs than physical
ones).
next prev parent reply other threads:[~2021-05-20 22:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-16 10:27 [PATCH] rcu/tree: consider time a VM was suspended Sergey Senozhatsky
2021-05-17 16:23 ` Paul E. McKenney
2021-05-18 1:41 ` Sergey Senozhatsky
2021-05-18 23:15 ` Paul E. McKenney
2021-05-20 5:50 ` Sergey Senozhatsky
2021-05-20 14:57 ` Paul E. McKenney
2021-05-20 22:34 ` Sergey Senozhatsky [this message]
2021-05-21 0:15 ` Paul E. McKenney
2021-05-20 6:18 ` Sergey Senozhatsky
2021-05-20 14:53 ` Paul E. McKenney
2021-05-20 22:24 ` Sergey Senozhatsky
2021-05-21 0:14 ` Paul E. McKenney
2021-05-21 6:42 ` Sergey Senozhatsky
2021-05-21 14:02 ` Paul E. McKenney
2021-05-21 6:36 ` Sergey Senozhatsky
2021-05-21 14:01 ` Paul E. McKenney
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