linux-kernel - Re: microcode loading got really slow.

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Date:	Thu, 23 May 2013 12:16:34 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Ming Lei <tom.leiming@...il.com>, Dave Jones <davej@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>, x86@...nel.org,
	fenghua.yu@...el.com
Subject: Re: microcode loading got really slow.

At Thu, 23 May 2013 10:06:56 +0200,
Takashi Iwai wrote:
> 
> At Thu, 23 May 2013 15:45:32 +0800,
> Ming Lei wrote:
> > 
> > On Thu, May 23, 2013 at 11:39 AM, Dave Jones <davej@...hat.com> wrote:
> > >  > On 05/21/2013 04:03 PM, Dave Jones wrote:
> > >  >
> > >  > [   72.318133] microcode: CPU1 sig=0x306c3, pf=0x2, revision=0x6
> > >  > [  132.446449] microcode: CPU2 sig=0x306c3, pf=0x2, revision=0x6
> > >  > [  192.573101] microcode: CPU3 sig=0x306c3, pf=0x2, revision=0x6
> > >  > [  252.702055] microcode: Microcode Update Driver: v2.00 <tigran@...azian.fsnet.co.uk>, Peter Oruba
> > >  >
> > >  > For some reason the events for udev seem to be getting delayed 60s
> > >  > for each core.
> > >
> > > Screwed up my .config, and had CONFIG_FW_LOADER_USER_HELPER inadvertantly set
> > > Odd though that it causes that 60 second delay, given that it's supposedly a
> > > 'fallback' when the direct loading fails.
> > 
> > udevd has the ugly problem previously at some situations(for example,
> > request_firmware called in probe(), and that is why direct loading is
> > introduced),
> > but not sure why the direct loading is failed first.
> 
> The microcode update is optional, so it's no error even if the
> microcode firmwares are not found.
> 
> But yes, this seems happening during the module probing.  The lines
> "microcde: CPU..." show before "microcode: Microcode Update
> Driver...", which means the f/w loading has been done before finishing
> the module load.
> 
> I thought (or hoped) this mess (60s stalls) was fixed in the recent
> udev, but apparently not...?

Thinking on this again, if the user-space continues to be broken in
that point, we should provide request_firmware() variant without udev,
e.g. request_firmware_direct(), and use it in known places like this?


Takashi
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