From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
pmladek@suse.com, sergey.senozhatsky@gmail.com,
linux-kernel@vger.kernel.org, mingo@kernel.org,
tglx@linutronix.de
Subject: Re: [PATCH 3/3] early_printk: Add simple serialization to early_vprintk()
Date: Wed, 4 Oct 2017 08:14:31 -0700 [thread overview]
Message-ID: <20171004151431.GI3521@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171004145247.4tp6r6ds6e5pkut5@hirez.programming.kicks-ass.net>
On Wed, Oct 04, 2017 at 04:52:47PM +0200, Peter Zijlstra wrote:
> On Wed, Oct 04, 2017 at 10:43:54AM -0400, Steven Rostedt wrote:
> >
> > My question is not about ordering, but about coherency. Can you have
> > one CPU read a variable that goes into cache, and keep using the cached
> > variable every time the program asks to read it, instead of going out
> > to memory.
>
> No, not on a coherent system.
What Peter said. And if you use READ_ONCE() for the reads, than as
far as I know, all the systems that the Linux kernel supports are
coherent systems.
Thanx, Paul
next prev parent reply other threads:[~2017-10-04 15:14 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-28 12:18 [PATCH 0/3] printk: Add force_early_printk boot param Peter Zijlstra
2017-09-28 12:18 ` [PATCH 1/3] printk: Fix kdb_trap_printk placement Peter Zijlstra
2017-10-03 22:10 ` Steven Rostedt
2017-10-05 13:38 ` Petr Mladek
2017-10-05 13:42 ` Peter Zijlstra
2017-10-09 15:05 ` Petr Mladek
2017-10-12 9:45 ` Petr Mladek
2017-10-12 10:03 ` Petr Mladek
2017-10-12 11:34 ` Peter Zijlstra
2017-10-12 11:52 ` Greg Kroah-Hartman
2017-10-12 12:08 ` Greg Kroah-Hartman
2017-10-12 18:11 ` Joe Perches
2017-10-13 14:23 ` Petr Mladek
2017-10-12 11:30 ` Peter Zijlstra
2017-09-28 12:18 ` [PATCH 2/3] early_printk: Add force_early_printk kernel parameter Peter Zijlstra
2017-09-28 15:41 ` Randy Dunlap
2017-09-28 16:07 ` Peter Zijlstra
2017-09-28 17:05 ` Randy Dunlap
2017-10-03 22:18 ` Steven Rostedt
2017-10-12 10:24 ` Petr Mladek
2017-10-12 11:39 ` Peter Zijlstra
2017-10-13 13:06 ` Petr Mladek
2017-10-13 13:20 ` Peter Zijlstra
2017-10-13 13:30 ` Steven Rostedt
2017-09-28 12:18 ` [PATCH 3/3] early_printk: Add simple serialization to early_vprintk() Peter Zijlstra
2017-10-03 22:24 ` Steven Rostedt
2017-10-04 9:08 ` Peter Zijlstra
2017-10-04 13:04 ` Steven Rostedt
2017-10-04 13:08 ` Peter Zijlstra
2017-10-04 14:17 ` Paul E. McKenney
2017-10-04 14:43 ` Steven Rostedt
2017-10-04 14:52 ` Peter Zijlstra
2017-10-04 15:02 ` Steven Rostedt
2017-10-04 15:14 ` Paul E. McKenney [this message]
2017-10-04 15:24 ` Peter Zijlstra
2017-10-04 15:38 ` Paul E. McKenney
2017-09-28 16:02 ` [PATCH 0/3] printk: Add force_early_printk boot param Sergey Senozhatsky
2017-09-28 16:17 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2016-10-18 17:08 [PATCH 0/3] make printk work again Peter Zijlstra
2016-10-18 17:08 ` [PATCH 3/3] early_printk: Add simple serialization to early_vprintk() Peter Zijlstra
2016-10-18 17:19 ` Steven Rostedt
2016-10-18 17:30 ` Peter Zijlstra
2016-10-18 17:53 ` Steven Rostedt
2016-11-29 14:10 ` Petr Mladek
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