[PATCH] ARM: smp: Introduce ARCH_HAS_COMMON_CORES_CLOCK to speed-up boot

Santosh Shilimkar santosh.shilimkar at ti.com
Thu Jan 20 10:36:35 EST 2011

> -----Original Message-----
> From: Rob Herring [mailto:robherring2 at gmail.com]
> Sent: Thursday, January 20, 2011 8:44 PM
> To: Santosh Shilimkar
> Cc: linux-arm-kernel at lists.infradead.org; Russell King; linux-
> omap at vger.kernel.org; Linus Walleij
> Subject: Re: [PATCH] ARM: smp: Introduce ARCH_HAS_COMMON_CORES_CLOCK
> to speed-up boot
> On 01/20/2011 03:42 AM, Santosh Shilimkar wrote:
> > On some architectures, secondary cores shares clock with primiary
> > core and hence scale together. Hence secondary core lpj
> calibration
> > is not necessary and can be skipped to save considerable time.
> >
> > This can speed up the secondary cpu boot and hotplug cpu online
> > paths.
> >
> > Discussion thread:
> > 	http://www.spinics.net/lists/arm-kernel/msg111124.html
> >
> There's already one way to do this with pre-calculated lpj.
How about the hot-plug path? This is not for just boot.

> Also, this isn't multi-platform friendly. You could accomplish the
> same
> thing using the clock api to get the core frequency of each core and
> only calculate lpj if the frequency is different.
May be but what's wrong with the obvious approach which is
completely non-intrusive.
Why is not multi-platform friendly ?
Archs can choose not to select this option.


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