From: xiang xiao <xiaoxiang781216@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
linux-kernel@vger.kernel.org, Xiang Xiao <xiaoxiang@xiaomi.com>
Subject: Re: [PATCH] printk: add KERN_NOTIME to skip the timestamp
Date: Wed, 13 Feb 2019 16:52:49 +0800 [thread overview]
Message-ID: <CAH2Cfb-vv8cAUqpv3vKMiYEg_W=5CGDqZXA9BkCukRONahWoxg@mail.gmail.com> (raw)
In-Reply-To: <20190213080852.GA1702@jagdpanzerIV>
On Wed, Feb 13, 2019 at 4:08 PM Sergey Senozhatsky
<sergey.senozhatsky.work@gmail.com> wrote:
>
> On (02/13/19 15:14), xiang xiao wrote:
> >
> > But how can I precisely control timestamp on/off per message
> > through sysfs node?
> >
>
> Hmm. I don't know how many kernel printk-s you have and how often
> do you write to kmsg.
It depend on use case, but I plan to create a generic driver which
could reuse by all rpmsg based remoteproc.
This is the driver for upstream:
https://github.com/thesofproject/linux/pull/177/commits/a0b7009fede5552dc98733f2996a8140bff62455
so we need more precisely control here.
> I was thinking about something like this:
>
> echo 0 > /...printk.../time
> dump buffer to /dev/kmsg
> echo 1 > /...printk../time
>
Another problem is how to control sysfs node from driver code
naturally, the concurrency and global side effect also need to
address.
> - If you would have several kernel printk-s in the meantime, then
> those would not have timestamps, but you kinda can roughly guess
> it
>
> write [1243] foo > /dev/kmsg
> write [1244] foo > /dev/kmsg
> << printk(bar) <timestamp ~[1244,1245]>
> write [1245] foo > /dev/kmsg
>
> Maybe this won't suffice.
>
> -ss
next prev parent reply other threads:[~2019-02-13 8:53 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 18:11 [PATCH] printk: add KERN_NOTIME to skip the timestamp Xiang Xiao
2019-02-12 19:46 ` Steven Rostedt
2019-02-13 6:19 ` xiang xiao
2019-02-13 6:29 ` Sergey Senozhatsky
2019-02-13 6:38 ` Sergey Senozhatsky
2019-02-13 7:14 ` xiang xiao
2019-02-13 8:08 ` Sergey Senozhatsky
2019-02-13 8:52 ` xiang xiao [this message]
2019-02-13 13:19 ` Petr Mladek
2019-02-13 13:49 ` xiang xiao
2019-02-13 13:47 ` Steven Rostedt
2019-02-13 14:00 ` xiang xiao
2019-02-13 14:31 ` Steven Rostedt
2019-02-13 16:25 ` xiang xiao
2019-02-14 1:26 ` Sergey Senozhatsky
2019-02-14 8:48 ` Petr Mladek
2019-02-13 0:48 ` Sergey Senozhatsky
2019-02-13 6:25 ` xiang xiao
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