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From: Peter Zijlstra <peterz@infradead.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Andrea Parri <andrea.parri@amarulasolutions.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Brendan Higgins <brendanhiggins@google.com>,
	John Ogness <john.ogness@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v4 0/9] printk: new ringbuffer implementation
Date: Fri, 6 Sep 2019 16:22:35 +0200	[thread overview]
Message-ID: <20190906142235.GY2386@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190906140126.GY2349@hirez.programming.kicks-ass.net>

On Fri, Sep 06, 2019 at 04:01:26PM +0200, Peter Zijlstra wrote:
> On Fri, Sep 06, 2019 at 02:42:11PM +0200, Petr Mladek wrote:
> > 7. People would complain when continuous lines become less
> >    reliable. It might be most visible when mixing backtraces
> >    from all CPUs. Simple sorting by prefix will not make
> >    it readable. The historic way was to synchronize CPUs
> >    by a spin lock. But then the cpu_lock() could cause
> >    deadlock.
> 
> Why? I'm running with that thing on, I've never seen a deadlock ever
> because of it. In fact, i've gotten output that is plain impossible with
> the current junk.
> 
> The cpu-lock is inside the all-backtrace spinlock, not outside. And as I
> said yesterday, only the lockless console has any wait-loops while
> holding the cpu-lock. It _will_ make progress.

Oooh, I think I see. So one solution would be to pass the NMI along in
chain like.  Send it to a single CPU at a time, when finished, send it
to the next.

  reply	other threads:[~2019-09-06 14:22 UTC|newest]

Thread overview: 134+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-07 22:26 [RFC PATCH v4 0/9] printk: new ringbuffer implementation John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 1/9] printk-rb: add a new printk " John Ogness
2019-08-20  8:15   ` numlist_pop(): " Petr Mladek
2019-08-21  5:41     ` John Ogness
2019-09-04 12:19     ` Peter Zijlstra
2019-08-20  8:22   ` assign_desc() barriers: " Petr Mladek
2019-08-20 14:14     ` Petr Mladek
2019-08-21  5:52       ` John Ogness
2019-08-22 11:53         ` Petr Mladek
2019-08-25  2:06           ` John Ogness
2019-08-26  8:21             ` John Ogness
2019-08-20  8:55   ` comments style: " Petr Mladek
2019-08-20  9:27     ` Sergey Senozhatsky
2019-08-21  5:46       ` John Ogness
2019-08-22 13:50         ` Petr Mladek
2019-08-22 17:38           ` Andrea Parri
2019-08-23 10:47             ` Petr Mladek
2019-08-23 14:27               ` Andrea Parri
2019-08-23  9:49           ` Sergey Senozhatsky
2019-08-23  5:54         ` Sergey Senozhatsky
2019-08-23 10:29           ` Petr Mladek
2019-08-21  5:42     ` John Ogness
2019-08-22 12:44       ` Petr Mladek
2019-08-20 13:50   ` dataring_push() barriers " Petr Mladek
2019-08-25  2:42     ` John Ogness
2019-08-27 14:36       ` Petr Mladek
2019-08-28 13:43         ` John Ogness
2019-08-20 15:12   ` datablock reuse races " Petr Mladek
2019-08-23  9:21   ` numlist_push() barriers " Petr Mladek
2019-08-26  8:34     ` Andrea Parri
2019-08-26  8:43       ` Andrea Parri
2019-08-26 14:10       ` Petr Mladek
2019-08-26 16:01         ` Andrea Parri
2019-08-26 22:36     ` John Ogness
2019-08-27  7:40       ` Petr Mladek
2019-08-27 14:28         ` John Ogness
2019-08-27 15:07           ` Petr Mladek
2019-08-28 10:24             ` John Ogness
2019-08-23 17:18   ` numlist API " Petr Mladek
2019-08-26 23:57     ` John Ogness
2019-08-27 13:03       ` Petr Mladek
2019-08-28  7:13         ` John Ogness
2019-08-28  8:58           ` Petr Mladek
2019-08-28 14:03             ` John Ogness
2019-08-29 11:28               ` Petr Mladek
2019-09-03  7:58         ` Sergey Senozhatsky
2019-08-30 14:48   ` dataring " Petr Mladek
2019-08-07 22:26 ` [RFC PATCH v4 2/9] printk-rb: add test module John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 3/9] printk-rb: fix missing includes/exports John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 4/9] printk-rb: initialize new descriptors as invalid John Ogness
2019-08-20  9:23   ` Petr Mladek
2019-08-20 10:16     ` Sergey Senozhatsky
2019-08-21  5:56     ` John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 5/9] printk-rb: remove extra data buffer size allocation John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 6/9] printk-rb: adjust test module ringbuffer sizes John Ogness
2019-08-19 21:29   ` [PATCH] printk-rb: fix test module macro usage John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 7/9] printk-rb: increase size of seq and size variables John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 8/9] printk-rb: new functionality to support printk John Ogness
2019-08-20  9:59   ` Sergey Senozhatsky
2019-08-21  5:47     ` John Ogness
2019-08-07 22:26 ` [RFC PATCH v4 9/9] printk: use a new ringbuffer implementation John Ogness
2019-08-08 19:07   ` Linus Torvalds
2019-08-08 22:55     ` John Ogness
2019-08-08 23:33       ` Linus Torvalds
2019-08-08 23:45         ` Steven Rostedt
2019-08-09  0:21           ` Linus Torvalds
2019-08-09  0:48             ` Steven Rostedt
2019-08-09  1:15               ` Linus Torvalds
2019-08-09 11:15                 ` Thomas Gleixner
2019-08-09 16:00                   ` Linus Torvalds
2019-08-09 20:07                     ` Thomas Gleixner
2019-08-09 20:20                       ` Linus Torvalds
2019-08-09  6:14     ` Peter Zijlstra
2019-08-09  7:08       ` John Ogness
2019-08-09 15:57       ` Linus Torvalds
2019-08-10  5:53         ` Thomas Gleixner
2019-09-10  3:19           ` Sergey Senozhatsky
2019-08-12  9:54       ` Geert Uytterhoeven
2019-08-16  5:46   ` Dave Young
2019-08-16  5:46     ` Dave Young
2019-08-16  5:54     ` Dave Young
2019-08-16  5:54       ` Dave Young
2019-08-16  9:40     ` John Ogness
2019-08-16  9:40       ` John Ogness
2019-09-04 12:35 ` [RFC PATCH v4 0/9] printk: " Peter Zijlstra
2019-09-05 13:05   ` Petr Mladek
2019-09-05 14:31     ` Peter Zijlstra
2019-09-05 15:38       ` Thomas Gleixner
2019-09-05 16:11         ` Steven Rostedt
2019-09-05 21:10           ` John Ogness
2019-09-06  9:39           ` Petr Mladek
2019-09-09 14:11           ` printk meeting at LPC Thomas Gleixner
2019-09-13 13:26             ` John Ogness
2019-09-13 14:48               ` Daniel Vetter
2019-09-15 13:47                 ` John Ogness
2019-09-16  8:44                   ` Daniel Vetter
2019-09-16  4:30               ` Tetsuo Handa
2019-09-16 10:46                 ` Petr Mladek
2019-09-16 13:43                   ` Steven Rostedt
2019-09-16 14:28                     ` John Ogness
2019-09-17  8:11                       ` Petr Mladek
2019-09-17  7:52                     ` Petr Mladek
2019-09-17 13:02                       ` Steven Rostedt
2019-09-17 13:12                         ` Greg Kroah-Hartman
2019-09-17 13:37                           ` Steven Rostedt
2019-09-17 14:08                             ` Tetsuo Handa
2019-09-17  7:51                   ` Sergey Senozhatsky
2019-09-18  1:25               ` Sergey Senozhatsky
2019-09-18  2:08                 ` Steven Rostedt
2019-09-18  2:36                   ` Sergey Senozhatsky
2019-09-18  5:19                     ` Sergey Senozhatsky
2019-09-18  7:42                       ` John Ogness
2019-09-18  8:10                         ` Sergey Senozhatsky
2019-09-18  9:05                           ` John Ogness
2019-09-18  9:11                             ` Sergey Senozhatsky
2019-09-18 16:41                             ` Petr Mladek
2019-09-18 16:48                               ` Steven Rostedt
2019-09-24 14:24                                 ` Petr Mladek
2019-09-19  8:06                         ` Daniel Vetter
2019-09-18  7:33                     ` John Ogness
2019-09-18  8:08                       ` Sergey Senozhatsky
2019-10-04 14:48               ` Tony Asleson
2019-10-07 12:01                 ` Petr Mladek
2019-09-06  9:06       ` [RFC PATCH v4 0/9] printk: new ringbuffer implementation Peter Zijlstra
2019-09-06 10:09         ` Sergey Senozhatsky
2019-09-06 10:49           ` Peter Zijlstra
2019-09-06 13:44             ` Sergey Senozhatsky
2019-09-06 12:42         ` Petr Mladek
2019-09-06 14:01           ` Peter Zijlstra
2019-09-06 14:22             ` Peter Zijlstra [this message]
2019-09-06 19:53             ` Sergey Senozhatsky
2019-09-06 22:47             ` John Ogness
2019-09-08 22:18             ` Peter Zijlstra
2019-09-10  3:22             ` Sergey Senozhatsky

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