Re: [PATCH] printk: introduce should_ignore_loglevel()

From: Petr Mladek <pmladek@suse.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>, Jan Kara <jack@suse.cz>,
	Calvin Owens <calvinowens@fb.com>,
	linux-kernel@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH] printk: introduce should_ignore_loglevel()
Date: Fri, 24 Jun 2016 18:05:34 +0200	[thread overview]
Message-ID: <20160624160533.GI29718@pathway.suse.cz> (raw)
In-Reply-To: <20160623163302.761-1-sergey.senozhatsky@gmail.com>

On Fri 2016-06-24 01:33:02, Sergey Senozhatsky wrote:
> The thing here is this deferred `level >= console_loglevel' check. We are
> wasting CPU cycles on sprintfs/memcpy/etc. preparing the messages that we
> will eventually drop.
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  kernel/printk/printk.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 414a89f..bfb766b 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -987,6 +987,11 @@ module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
>  MODULE_PARM_DESC(ignore_loglevel,
>  		 "ignore loglevel setting (prints all kernel messages to the console)");
>  
> +static bool should_ignore_loglevel(int level)
> +{
> +	return (level >= console_loglevel && !ignore_loglevel);

The patch looks fine. It is nice optimization.

I was just quite confused by the name of this function. A function
called should_ignore_loglevel() should not return false when
ignore_loglevel variable is true.

I would call it ignore_message() or ignore_message_on_console() or so.

Best Regards,
Petr