From: Peter Zijlstra <peterz@infradead.org>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable
Date: Fri, 18 Dec 2015 11:29:02 +0000 [thread overview]
Message-ID: <20151218112902.GO6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5673DD60.7080302@linaro.org>
On Fri, Dec 18, 2015 at 10:18:08AM +0000, Daniel Thompson wrote:
> I'm not entirely sure that this is an improvement.
What I do these days is delete everything in vprintk_emit() and simply
call early_printk().
Kill the useless kmsg buffer crap and locking, just pound bytes to the
UART registers without anything in between.
The other semi usable solution is redirecting to trace_printk() and
recovering the trace buffers from your kdump. But I've found that
typically kdump doesn't work anymore if you properly wedge the machine.
So this is very much a second rate solution.
But this globally locked buffer, calling out to console drivers that do
locking and even scheduling, is an unreliable unfixable trainwreck that
I've given up on.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jiri Kosina <jikos@kernel.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"adi-buildroot-devel@lists.sourceforge.net"
<adi-buildroot-devel@lists.sourceforge.net>,
Cris <linux-cris-kernel@axis.com>,
Linux MIPS Mailing List <linux-mips@linux-mips.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>
Subject: Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable
Date: Fri, 18 Dec 2015 12:29:02 +0100 [thread overview]
Message-ID: <20151218112902.GO6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5673DD60.7080302@linaro.org>
On Fri, Dec 18, 2015 at 10:18:08AM +0000, Daniel Thompson wrote:
> I'm not entirely sure that this is an improvement.
What I do these days is delete everything in vprintk_emit() and simply
call early_printk().
Kill the useless kmsg buffer crap and locking, just pound bytes to the
UART registers without anything in between.
The other semi usable solution is redirecting to trace_printk() and
recovering the trace buffers from your kdump. But I've found that
typically kdump doesn't work anymore if you properly wedge the machine.
So this is very much a second rate solution.
But this globally locked buffer, calling out to console drivers that do
locking and even scheduling, is an unreliable unfixable trainwreck that
I've given up on.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jiri Kosina <jikos@kernel.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"adi-buildroot-devel@lists.sourceforge.net"
<adi-buildroot-devel@lists.sourceforge.net>,
Cris <linux-cris-kernel@axis.com>,
Linux MIPS Mailing List <linux-mips@linux-mips.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>
Subject: Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable
Date: Fri, 18 Dec 2015 12:29:02 +0100 [thread overview]
Message-ID: <20151218112902.GO6344@twins.programming.kicks-ass.net> (raw)
Message-ID: <20151218112902.RSbaPmcZf-1658oV81cX6nnfMlEgb_2yY2MHYtVI-MY@z> (raw)
In-Reply-To: <5673DD60.7080302@linaro.org>
On Fri, Dec 18, 2015 at 10:18:08AM +0000, Daniel Thompson wrote:
> I'm not entirely sure that this is an improvement.
What I do these days is delete everything in vprintk_emit() and simply
call early_printk().
Kill the useless kmsg buffer crap and locking, just pound bytes to the
UART registers without anything in between.
The other semi usable solution is redirecting to trace_printk() and
recovering the trace buffers from your kdump. But I've found that
typically kdump doesn't work anymore if you properly wedge the machine.
So this is very much a second rate solution.
But this globally locked buffer, calling out to console drivers that do
locking and even scheduling, is an unreliable unfixable trainwreck that
I've given up on.
WARNING: multiple messages have this Message-ID (diff)
From: peterz@infradead.org (Peter Zijlstra)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable
Date: Fri, 18 Dec 2015 12:29:02 +0100 [thread overview]
Message-ID: <20151218112902.GO6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5673DD60.7080302@linaro.org>
On Fri, Dec 18, 2015 at 10:18:08AM +0000, Daniel Thompson wrote:
> I'm not entirely sure that this is an improvement.
What I do these days is delete everything in vprintk_emit() and simply
call early_printk().
Kill the useless kmsg buffer crap and locking, just pound bytes to the
UART registers without anything in between.
The other semi usable solution is redirecting to trace_printk() and
recovering the trace buffers from your kdump. But I've found that
typically kdump doesn't work anymore if you properly wedge the machine.
So this is very much a second rate solution.
But this globally locked buffer, calling out to console drivers that do
locking and even scheduling, is an unreliable unfixable trainwreck that
I've given up on.
next prev parent reply other threads:[~2015-12-18 11:29 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-09 13:21 [PATCH v3 0/4] Cleaning printk stuff in NMI context Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` [PATCH v3 1/4] printk/nmi: Generic solution for safe printk in NMI Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 23:50 ` Andrew Morton
2015-12-09 23:50 ` Andrew Morton
2015-12-09 23:50 ` Andrew Morton
2015-12-10 15:26 ` Petr Mladek
2015-12-10 15:26 ` Petr Mladek
2015-12-10 15:26 ` Petr Mladek
2015-12-09 13:21 ` [PATCH v3 2/4] printk/nmi: Use IRQ work only when ready Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` [PATCH v3 3/4] printk/nmi: Warn when some message has been lost in NMI context Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-09 13:21 ` Petr Mladek
2015-12-11 11:10 ` Geert Uytterhoeven
2015-12-11 11:10 ` Geert Uytterhoeven
2015-12-11 11:10 ` Geert Uytterhoeven
2015-12-11 11:10 ` Geert Uytterhoeven
2015-12-11 12:41 ` Petr Mladek
2015-12-11 12:41 ` Petr Mladek
2015-12-11 12:41 ` Petr Mladek
2015-12-11 12:41 ` Petr Mladek
2015-12-11 12:47 ` Arnd Bergmann
2015-12-11 12:47 ` Arnd Bergmann
2015-12-11 12:47 ` Arnd Bergmann
2015-12-11 12:47 ` Arnd Bergmann
2015-12-11 12:50 ` Geert Uytterhoeven
2015-12-11 12:50 ` Geert Uytterhoeven
2015-12-11 12:50 ` Geert Uytterhoeven
2015-12-11 12:50 ` Geert Uytterhoeven
2015-12-11 12:50 ` Geert Uytterhoeven
2015-12-11 22:57 ` Andrew Morton
2015-12-11 22:57 ` Andrew Morton
2015-12-11 22:57 ` Andrew Morton
2015-12-11 22:57 ` Andrew Morton
2015-12-11 23:21 ` Russell King - ARM Linux
2015-12-11 23:21 ` Russell King - ARM Linux
2015-12-11 23:21 ` Russell King - ARM Linux
2015-12-11 23:21 ` Russell King - ARM Linux
2015-12-11 23:26 ` Jiri Kosina
2015-12-11 23:26 ` Jiri Kosina
2015-12-11 23:26 ` Jiri Kosina
2015-12-11 23:26 ` Jiri Kosina
2015-12-18 10:18 ` Daniel Thompson
2015-12-18 10:18 ` Daniel Thompson
2015-12-18 10:18 ` Daniel Thompson
2015-12-18 10:18 ` Daniel Thompson
2015-12-18 11:29 ` Peter Zijlstra [this message]
2015-12-18 11:29 ` Peter Zijlstra
2015-12-18 11:29 ` Peter Zijlstra
2015-12-18 11:29 ` Peter Zijlstra
2015-12-18 12:11 ` Peter Zijlstra
2015-12-18 12:11 ` Peter Zijlstra
2015-12-18 12:11 ` Peter Zijlstra
2015-12-18 12:11 ` Peter Zijlstra
2015-12-18 23:03 ` Andrew Morton
2015-12-18 23:03 ` Andrew Morton
2015-12-18 23:03 ` Andrew Morton
2015-12-18 23:03 ` Andrew Morton
2015-12-18 14:52 ` Petr Mladek
2015-12-18 14:52 ` Petr Mladek
2015-12-18 14:52 ` Petr Mladek
2015-12-18 14:52 ` Petr Mladek
2015-12-18 17:00 ` Daniel Thompson
2015-12-18 17:00 ` Daniel Thompson
2015-12-18 17:00 ` Daniel Thompson
2015-12-18 17:00 ` Daniel Thompson
2016-03-01 14:04 ` Daniel Thompson
2016-03-01 14:04 ` Daniel Thompson
2016-03-01 14:04 ` Daniel Thompson
2016-03-01 14:04 ` Daniel Thompson
2015-12-11 23:30 ` Andrew Morton
2015-12-11 23:30 ` Andrew Morton
2015-12-11 23:30 ` Andrew Morton
2015-12-11 23:30 ` Andrew Morton
2015-12-15 14:26 ` Petr Mladek
2015-12-15 14:26 ` Petr Mladek
2015-12-15 14:26 ` Petr Mladek
2015-12-15 14:26 ` Petr Mladek
2015-12-17 22:38 ` Andrew Morton
2015-12-17 22:38 ` Andrew Morton
2015-12-17 22:38 ` Andrew Morton
2015-12-17 22:38 ` Andrew Morton
2015-12-18 16:18 ` Petr Mladek
2015-12-18 16:18 ` Petr Mladek
2015-12-18 16:18 ` Petr Mladek
2015-12-18 16:18 ` Petr Mladek
2015-12-18 16:18 ` Petr Mladek
2015-12-18 16:18 ` Petr Mladek
2015-12-14 10:28 ` Daniel Thompson
2015-12-14 10:28 ` Daniel Thompson
2015-12-14 10:28 ` Daniel Thompson
2015-12-14 10:28 ` Daniel Thompson
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