From: 김창기 <changki.kim@samsung.com>
To: "'Greg KH'" <gregkh@linuxfoundation.org>
Cc: <pmladek@suse.com>, <sergey.senozhatsky@gmail.com>,
<rostedt@goodmis.org>, <john.ogness@linutronix.de>,
<masahiroy@kernel.org>, <rd.dunlap@gmail.com>, <krzk@kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: RE: printk: Add process name information to printk() output.
Date: Fri, 4 Sep 2020 18:31:13 +0900 [thread overview]
Message-ID: <000001d6829e$2226cc60$66746520$@samsung.com> (raw)
In-Reply-To: <20200904090535.GA2440145@kroah.com>
> On Fri, Sep 04, 2020 at 05:24:38PM +0900, Changki Kim wrote:
> > Printk() meesages are the most basic and useful debug method.
> > However, additional information needs in multi-processor.
> > If we add messages with processor id and process name, we can find a
> > problem only with messages when the problem occurs with H/W IP or CPU.
> > This is very useful in narrowing down the scope of the problems.
> >
> > Therefore, instead of trying to help buffering, let's try to help
> > reconstructing messages by saving caller information as of calling
> > log_store() and adding it as "[$processor_id: $process_name:
> $thread_id]"
> > upon printing to consoles.
> >
> > Some examples for console output:
> >
> > [ 0.059580] [0: swapper/0: 1] CPU: All CPU(s) started at
EL1i
> > [ 2.153157] [5: init: 1] migov: complete to probe
migov
> > [ 7.441317] [4: init: 1] NET: Registered protocol
family 39
> > [ 22.793389] [5: kworker/u16:1: 184] SMP: stopping secondary CPUs
> >
> > Signed-off-by: Changki Kim <changki.kim@samsung.com>
> > ---
> > kernel/printk/printk.c | 20 ++++++++++++++++++--
> > kernel/printk/printk_ringbuffer.h | 7 +++++++
> > lib/Kconfig.debug | 16 ++++++++++++++++
> > 3 files changed, 41 insertions(+), 2 deletions(-)
>
> Isn't the CPU number already present if you want it today? Why add it
> again?
>
> thanks,
>
> greg k-h
CPU number isn't present now. If I enabled PRINTK_CALLER,
then it is present cpu id or thread id.
The config isn't always present cpu id.
We need cpu id each each message.
Thanks.
next prev parent reply other threads:[~2020-09-04 9:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200904082449epcas2p4420d5df2083325b328a182c79f5c0948@epcas2p4.samsung.com>
2020-09-04 8:24 ` printk: Add process name information to printk() output Changki Kim
2020-09-04 9:05 ` Greg KH
2020-09-04 9:31 ` 김창기 [this message]
2020-09-04 10:34 ` 'Greg KH'
2020-09-07 1:48 ` 김창기
2020-09-04 9:47 ` John Ogness
2020-09-04 10:35 ` Greg KH
2020-09-04 19:27 ` Joe Perches
2020-09-04 12:45 ` Petr Mladek
2020-09-04 13:17 ` John Ogness
2020-09-04 15:13 ` Petr Mladek
2020-09-04 23:27 ` John Ogness
2020-09-07 9:28 ` 김창기
2020-09-07 9:54 ` Petr Mladek
2020-09-07 10:30 ` John Ogness
2020-09-07 15:47 ` Petr Mladek
2020-09-11 9:50 ` [POC] printk: Convert dict ring into array Petr Mladek
2020-09-11 10:32 ` Petr Mladek
2020-09-11 11:09 ` John Ogness
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