spinlocks

[Troy Benjegerdes]

On Wed, Jan 07, 2004 at 09:02:22AM -0600, Dave Engebretsen wrote:
>
> olof at austin.ibm.com wrote:
> >On Wed, 7 Jan 2004, Dave Engebretsen wrote:
> >
> >
> >>Is a single binary for Apple & pSeries a goal?  While it has some
> >>obvious advantages, there is likely to be a number of areas (the
> >>spinlock discussion being one) where the goals are quite different.
> >
> >
> >Are they really all that different? We need to keep the pSeries code
> >running smoothly on a small-config SMP machine too (i.e. p615 and the
> >like).
> >
> >
> >-Olof
>
> Maybe not - just raising the debate.  Nothing is all this will not keep
> the code running smoothly on small config p615 machines.  In many ways,
> the more advanced virtualaztion results in machines which are much
> smaller than anything else, so tuning for small is good for i/pSeries too.
>
> Everything being equal, I would just as soon see a common binary.  But
> items like HMT priorities are almost certainly going to exist in the Mac
> binaries -- frankly, in the scheme of things a few extra noops in the
> kernel are not going to be the performance bottleneck an end user sees.

Even if no distribution actually ships a common binary, I vote we need to
support it. The people MOST interested in a common binary are people
doing QA testing. If someone shows up on linuxppc64-dev with a strange
kernel bug, the first thing I would want to say is "Can you reproduce
this bug on THIS binary kernel image?".

I have both pmac and PReP machines, and even a 5-10% performance hit
would be worth it to not have to spend the time to compile a different
kernel for both machines.

Supporting a common binary makes it easier to get new users up and
running so they don't have to figure out which one of 15 different
configurations they actually need on their hardware.

Oh yeah, and don't forget installers!! *one* kernel binary for
installers is SO much easier.

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