linux-kernel - Re: [PATCH RESEND] CPU hotplug,x86 Microcode: Don't request microcode from userspace unnecessarily

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Date:	Mon, 10 Oct 2011 23:13:00 +0200
From:	Borislav Petkov <bp@...64.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>, Borislav Petkov <bp@...64.org>,
	"tigran@...azian.fsnet.co.uk" <tigran@...azian.fsnet.co.uk>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
	"Herrmann3, Andreas" <Andreas.Herrmann3@....com>,
	"amd64-microcode@...64.org" <amd64-microcode@...64.org>,
	Tejun Heo <tj@...nel.org>,
	Linux PM mailing list <linux-pm@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] CPU hotplug,x86 Microcode: Don't request
 microcode from userspace unnecessarily

On Mon, Oct 10, 2011 at 04:58:02PM -0400, Rafael J. Wysocki wrote:
> On Sunday, October 09, 2011, Srivatsa S. Bhat wrote:
> > Requesting the microcode from userspace *every time* when onlining CPUs
> > (during a CPU hotplug operation) is unnecessary.
> > 
> > So, this patch ensures that once the kernel gets the microcode after booting,
> > it is not freed nor invalidated when a CPU goes offline, so that it can be
> > reused when that CPU comes back online, without requesting userspace for it
> > again. As a result, the CPU hotplug operations become faster as well.
> > 
> > Tested-by: Borislav Petkov <bp@...64.org>
> > Acked-by: Borislav Petkov <bp@...64.org>
> > 
> > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> 
> Fine by me.  I wonder who should take this?

Ingo, most probably. ucode stuff goes in through -tip.

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Boris.

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