[PATCH 6/6] powerpc: Enable sparse irq_descs on powerpc

Grant Likely grant.likely at secretlab.ca
Thu Oct 15 11:33:17 EST 2009

On Wed, Oct 14, 2009 at 5:51 PM, Michael Ellerman
<michael at ellerman.id.au> wrote:
> On Wed, 2009-10-14 at 12:44 -0600, Grant Likely wrote:
>> Why not make sparse IRQs manditory for all platforms?  Is there a
>> performance concern with doing so?  From a maintenance perspective,
>> I'd rather see IRQ descs manged in one way only to keep the code
>> simple.
> I agree on the maintenance angle. My thinking was we'd run with it
> optional but default y for a release or two, and if no one complains we
> can make it mandatory.
> It does make some code paths bigger, and looking up an irq_desc is going
> to take slightly more cycles. I don't think it's a big issue, but I
> thought we should try it for a while before making it mandatory. The
> code has only been tested on x86 and sh as far as I know.

No guts, no glory.  I say throw it into linux-next to give it some
time before the next merge window.  I don't think you'll get any
better results by having it optional for a few releases (in fact, I
suspect that people who do have problems will just end up turning it
off and waiting for someone else to report/fix the problems).  If this
is the direction IRQ handling is going, then just make the change and
force any bugs to be dealt with before the next release.

> ps. thanks for the review

You're welcome.


Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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