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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH] sysrq show-all-cpus
Date: Tue, 11 Mar 2008 19:12:54 +1100
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Cc: Randy Dunlap <randy.dunlap@oracle.com>, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org, lwoodman@redhat.com
References: <20080310133242.0ab69084@bree.surriel.com> <20080310104628.b70af419.randy.dunlap@oracle.com> <20080310140315.1a451092@bree.surriel.com>
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On Tuesday 11 March 2008 05:03, Rik van Riel wrote:
> SysRQ-P is not always useful on SMP systems, since it usually ends up
> showing the backtrace of a CPU that is doing just fine, instead of the
> backtrace of the CPU that is having problems.
>
> This patch adds SysRQ show-all-cpus(L), which shows the backtrace of every
> active CPU in the system.  It skips idle CPUs because some SMP systems are
> just too large and we already know what the backtrace of the idle task
> looks like.
>

Yeah we need something like this. I prefer mine though ;) It shows
registers as well as stack...

http://groups.google.com.au/group/fa.linux.kernel/msg/3cd0288f7fd3be2c?dmode=source&output=gplain

It prints just a single CPU at a time, but cycles through each one.
An alternative might be to have one sysrq key used to cycle between
CPUs, and sysrq+P could then just print out a trace from the selected
CPU...


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