linux-kernel - Re: [PATCH] Driver core: Reduce the level of request

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Message-Id: <201003152227.11295.rjw@sisk.pl>
Date:	Mon, 15 Mar 2010 22:27:11 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Greg KH <greg@...ah.com>
Cc:	Jaswinder Singh Rajput <jaswinderlinux@...il.com>,
	Greg KH <gregkh@...e.de>, LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] Driver core: Reduce the level of request_firmware() messages

On Monday 15 March 2010, Greg KH wrote:
> On Mon, Mar 01, 2010 at 01:43:54AM +0530, Jaswinder Singh Rajput wrote:
> > Hello Rafael,
> > 
> > On Mon, Mar 1, 2010 at 1:24 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > > On Sunday 28 February 2010, Jaswinder Singh Rajput wrote:
> > >>
> > >> On Sun, 2010-02-28 at 13:13 +0100, Rafael J. Wysocki wrote:
> > >> > On Sunday 28 February 2010, Jaswinder Singh Rajput wrote:
> > >> > > On Sun, Feb 28, 2010 at 2:13 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > >> > > > From: Rafael J. Wysocki <rjw@...k.pl>
> > >> > > >
> > >> > > > The messages from _request_firmware() informing that firmware is
> > >> > > > being requested or built-in firmware is going to be used are printed
> > >> > > > at KERN_INFO, which produces lots of noise on systems with huge
> > >> > > > numbers of AMD CPUs.  Reduce the level of these messages to
> > >> > > > KERN_DEBUG to get rid of that noise.
> > >> > > >
> > >> > >
> > >> > > Which firmware we are using is very useful information. Because of
> > >> > > huge numbers of CPUs it seems noise then better provide the
> > >> > > information for first cpu and for the rest of the CPUs you can show by
> > >> > > KERN_DEBUG.
> > >> >
> > >> > That would have been better indeed, but the problem is _request_firmware()
> > >> > doesn't allow us to change the level of its messages on demand.
> > >>
> > >> Can we try this :
> > >>
> > >>       if (smp_processor_id())
> > >>               dev_dbg(..);
> > >>       else
> > >>               dev_info(..);
> > >
> > > Well, it doesn't look particularly nice, does it?
> > >
> > > Besides, say we're requesting firmware for a non-CPU device which happens
> > > to run on CPU1.  Then, dev_dbg() will be used, which most likely is not what we
> > > want.
> > >
> > 
> > Yes, you are right. But atleast can you try it once and show the
> > output with and without this.
> 
> Was there ever a resolution to this?

Nope.

> Rafael, do you want me to apply your original patch now?

I still think it's a good idea.  The information about what firmware is being
used doesn't seem to be very useful for anything but debugging, so I think
KERN_DEBUG is actually the right level for these messages.

Rafael
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