From: Jiri Kosina <jkosina@suse.cz>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Jörn Engel" <joern@logfs.org>, "Rik van Riel" <riel@redhat.com>,
linux-kernel@vger.kernel.org, peterz@infradead.org,
akpm@linux-foundation.org, cxie@redhat.com,
"Jiri Slaby" <jslaby@suse.cz>
Subject: Re: [PATCH] printk: Print cpu number along with time
Date: Fri, 25 Apr 2014 00:12:06 +0200 (CEST) [thread overview]
Message-ID: <alpine.LNX.2.00.1404250005020.8903@pobox.suse.cz> (raw)
In-Reply-To: <20140424195821.GA3092@kroah.com>
On Thu, 24 Apr 2014, Greg Kroah-Hartman wrote:
> > +#ifdef CONFIG_PRINTK_CPU
> > + if (!buf)
> > + return snprintf(NULL, 0, "[%5lu.000000,%02x] ",
>
> %02x for a cpu? What happens on machines with 8k cpus?
Ummm ... what issue do you see here, Greg? It'll print 0x1f40, no?
> And is this really an issue? Debugging by using printk is fun, but not
> really something that people need to add a cpu number to. Why not just
> use a tracepoint in your code to get the needed information instead?
Well, if you have dmesg dump from panic that happens every other year, and
you have to do post-mortem analysis on it, I am pretty sure you would love
to be able to figure out how the stack traces would look like without
inter-CPU interleaving. And I am pretty sure you wouldn't want to
insert/enable a tracepoint and wait another two years for the bug to
trigger again.
--
Jiri Kosina
SUSE Labs
next prev parent reply other threads:[~2014-04-24 22:12 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-23 16:53 [PATCH RFC] sysrq: rcu-ify __handle_sysrq Rik van Riel
2014-04-23 20:04 ` Andrew Morton
2014-04-23 20:44 ` Rik van Riel
2014-04-23 21:39 ` Jiri Kosina
2014-04-23 21:41 ` Andrew Morton
2014-04-23 21:44 ` Jiri Kosina
2014-04-23 21:49 ` Andrew Morton
2014-04-23 21:37 ` Jiri Kosina
2014-04-23 21:42 ` Rik van Riel
2014-04-23 21:51 ` Jiri Kosina
2014-04-24 1:46 ` Paul E. McKenney
2014-04-24 13:04 ` [PATCH RFC] sysrq,rcu: suppress RCU stall warnings while sysrq runs Rik van Riel
2014-04-24 15:16 ` Paul E. McKenney
2014-04-25 5:35 ` Mike Galbraith
2014-04-24 0:52 ` [PATCH RFC] sysrq: rcu-ify __handle_sysrq Jörn Engel
2014-04-24 19:40 ` [PATCH] printk: Print cpu number along with time Jörn Engel
2014-04-24 19:58 ` Greg Kroah-Hartman
2014-04-24 21:23 ` Jörn Engel
2014-04-24 22:12 ` Jiri Kosina [this message]
2014-04-24 22:18 ` David Rientjes
2014-04-24 22:21 ` Jiri Kosina
2014-04-24 23:29 ` Jörn Engel
2014-04-24 22:20 ` Greg Kroah-Hartman
2014-04-28 23:40 ` Jörn Engel
2014-04-29 0:22 ` Andrew Morton
2014-06-04 23:15 ` Jörn Engel
2014-06-04 23:28 ` Andrew Morton
2014-06-04 23:49 ` Jörn Engel
2014-09-09 17:16 ` Jörn Engel
2014-09-10 21:26 ` Andrew Morton
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