From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 1/4] printk/nmi: generic solution for safe printk in NMI
Date: Fri, 28 Apr 2017 01:35:32 +0000 [thread overview]
Message-ID: <20170428013532.GB383@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20170427121458.2be577cc@gandalf.local.home>
On (04/27/17 12:14), Steven Rostedt wrote:
[..]
> I tried this patch. It's better because I get the end of the trace, but
> I do lose the beginning of it:
>
> ** 196358 printk messages dropped ** [ 102.321182] perf-5981 0.... 12983650us : d_path <-seq_path
many thanks!
so we now drop messages from logbuf, not from per-CPU buffers. that
"queue printk_deferred irq_work on every online CPU when we bypass per-CPU
buffers from NMI" idea *probably* might help here - we need someone to emit
messages from the logbuf while we printk from NMI. there is still a
possibility that we can drop messages, though, since log_store() from NMI
CPU can be much-much faster than call_console_drivers() on other CPU.
-ss
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Daniel Thompson <daniel.thompson@linaro.org>,
Jiri Kosina <jkosina@suse.com>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Chris Metcalf <cmetcalf@ezchip.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-arm-kernel@lists.infradead.org,
adi-buildroot-devel@lists.sourceforge.net,
linux-cris-kernel@axis.com, linux-mips@linux-mips.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
Jan Kara <jack@suse.cz>, Ralf Baechle <ralf@linux-mips.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH v5 1/4] printk/nmi: generic solution for safe printk in NMI
Date: Fri, 28 Apr 2017 10:35:32 +0900 [thread overview]
Message-ID: <20170428013532.GB383@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20170427121458.2be577cc@gandalf.local.home>
On (04/27/17 12:14), Steven Rostedt wrote:
[..]
> I tried this patch. It's better because I get the end of the trace, but
> I do lose the beginning of it:
>
> ** 196358 printk messages dropped ** [ 102.321182] perf-5981 0.... 12983650us : d_path <-seq_path
many thanks!
so we now drop messages from logbuf, not from per-CPU buffers. that
"queue printk_deferred irq_work on every online CPU when we bypass per-CPU
buffers from NMI" idea *probably* might help here - we need someone to emit
messages from the logbuf while we printk from NMI. there is still a
possibility that we can drop messages, though, since log_store() from NMI
CPU can be much-much faster than call_console_drivers() on other CPU.
-ss
WARNING: multiple messages have this Message-ID (diff)
From: sergey.senozhatsky.work@gmail.com (Sergey Senozhatsky)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 1/4] printk/nmi: generic solution for safe printk in NMI
Date: Fri, 28 Apr 2017 10:35:32 +0900 [thread overview]
Message-ID: <20170428013532.GB383@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20170427121458.2be577cc@gandalf.local.home>
On (04/27/17 12:14), Steven Rostedt wrote:
[..]
> I tried this patch. It's better because I get the end of the trace, but
> I do lose the beginning of it:
>
> ** 196358 printk messages dropped ** [ 102.321182] perf-5981 0.... 12983650us : d_path <-seq_path
many thanks!
so we now drop messages from logbuf, not from per-CPU buffers. that
"queue printk_deferred irq_work on every online CPU when we bypass per-CPU
buffers from NMI" idea *probably* might help here - we need someone to emit
messages from the logbuf while we printk from NMI. there is still a
possibility that we can drop messages, though, since log_store() from NMI
CPU can be much-much faster than call_console_drivers() on other CPU.
-ss
next prev parent reply other threads:[~2017-04-28 1:35 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 11:48 [PATCH v5 0/4] Cleaning printk stuff in NMI context Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` [PATCH v5 1/4] printk/nmi: generic solution for safe printk in NMI Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-27 9:31 ` Russell King - ARM Linux
2016-04-27 9:31 ` Russell King - ARM Linux
2016-04-27 9:31 ` Russell King - ARM Linux
2017-04-19 17:13 ` Steven Rostedt
2017-04-19 17:13 ` Steven Rostedt
2017-04-19 17:13 ` Steven Rostedt
2017-04-19 17:21 ` Peter Zijlstra
2017-04-19 17:21 ` Peter Zijlstra
2017-04-19 17:21 ` Peter Zijlstra
2017-04-20 3:31 ` Sergey Senozhatsky
2017-04-20 3:31 ` Sergey Senozhatsky
2017-04-20 3:31 ` Sergey Senozhatsky
2017-04-20 13:11 ` Petr Mladek
2017-04-20 13:11 ` Petr Mladek
2017-04-20 13:11 ` Petr Mladek
2017-04-20 13:11 ` Petr Mladek
2017-04-21 1:57 ` Sergey Senozhatsky
2017-04-21 1:57 ` Sergey Senozhatsky
2017-04-21 1:57 ` Sergey Senozhatsky
2017-04-21 12:06 ` Petr Mladek
2017-04-21 12:06 ` Petr Mladek
2017-04-21 12:06 ` Petr Mladek
2017-04-24 2:17 ` Sergey Senozhatsky
2017-04-24 2:17 ` Sergey Senozhatsky
2017-04-24 2:17 ` Sergey Senozhatsky
2017-04-27 13:38 ` Petr Mladek
2017-04-27 13:38 ` Petr Mladek
2017-04-27 13:38 ` Petr Mladek
2017-04-27 14:31 ` Steven Rostedt
2017-04-27 14:31 ` Steven Rostedt
2017-04-27 14:31 ` Steven Rostedt
2017-04-27 15:28 ` Petr Mladek
2017-04-27 15:28 ` Petr Mladek
2017-04-27 15:28 ` Petr Mladek
2017-04-27 15:42 ` Steven Rostedt
2017-04-27 15:42 ` Steven Rostedt
2017-04-27 15:42 ` Steven Rostedt
2017-04-28 9:02 ` Peter Zijlstra
2017-04-28 9:02 ` Peter Zijlstra
2017-04-28 9:02 ` Peter Zijlstra
2017-04-28 13:44 ` Petr Mladek
2017-04-28 13:44 ` Petr Mladek
2017-04-28 13:44 ` Petr Mladek
2017-04-28 13:58 ` Peter Zijlstra
2017-04-28 13:58 ` Peter Zijlstra
2017-04-28 13:58 ` Peter Zijlstra
2017-04-28 14:47 ` Steven Rostedt
2017-04-28 14:47 ` Steven Rostedt
2017-04-28 14:47 ` Steven Rostedt
2017-04-27 16:14 ` Steven Rostedt
2017-04-27 16:14 ` Steven Rostedt
2017-04-27 16:14 ` Steven Rostedt
2017-04-28 1:35 ` Sergey Senozhatsky [this message]
2017-04-28 1:35 ` Sergey Senozhatsky
2017-04-28 1:35 ` Sergey Senozhatsky
2017-04-28 12:57 ` Petr Mladek
2017-04-28 12:57 ` Petr Mladek
2017-04-28 12:57 ` Petr Mladek
2017-04-28 14:16 ` Steven Rostedt
2017-04-28 14:16 ` Steven Rostedt
2017-04-28 14:16 ` Steven Rostedt
2017-04-28 1:25 ` Sergey Senozhatsky
2017-04-28 1:25 ` Sergey Senozhatsky
2017-04-28 1:25 ` Sergey Senozhatsky
2017-04-28 12:38 ` Petr Mladek
2017-04-28 12:38 ` Petr Mladek
2017-04-28 12:38 ` Petr Mladek
2016-04-21 11:48 ` [PATCH v5 2/4] printk/nmi: warn when some message has been lost in NMI context Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-27 9:34 ` Russell King - ARM Linux
2016-04-27 9:34 ` Russell King - ARM Linux
2016-04-27 9:34 ` Russell King - ARM Linux
2016-04-21 11:48 ` [PATCH v5 3/4] printk/nmi: increase the size of NMI buffer and make it configurable Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` [PATCH v5 4/4] printk/nmi: flush NMI messages on the system panic Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-21 11:48 ` Petr Mladek
2016-04-23 3:49 ` Sergey Senozhatsky
2016-04-23 3:49 ` Sergey Senozhatsky
2016-04-23 3:49 ` Sergey Senozhatsky
2016-04-26 14:21 ` Petr Mladek
2016-04-26 14:21 ` Petr Mladek
2016-04-26 14:21 ` Petr Mladek
2016-04-27 0:34 ` Sergey Senozhatsky
2016-04-27 0:34 ` Sergey Senozhatsky
2016-04-27 0:34 ` Sergey Senozhatsky
2016-04-27 0:36 ` [PATCH v5 0/4] Cleaning printk stuff in NMI context Sergey Senozhatsky
2016-04-27 0:36 ` Sergey Senozhatsky
2016-04-27 0:36 ` Sergey Senozhatsky
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