Re: [PATCH 1/3] Separate IRQ-stacks from 4K-stacks option

[Martin J. Bligh]

--Hugh Dickins <hugh@xxxxxxxxxxx> wrote (on Friday, September 10, 2004 16:07:21 +0100):

> On Fri, 10 Sep 2004, Martin J. Bligh wrote:
>> 
>> I agree about killing anything but 4K stacks though - having the single
>> page is very compelling - not only can we allocate it easier, but we can
>> also use cache-hot pages from the hot list.
> 
> I think we all agree that's a promising future, and a good discipline.
> But I'm not the only one to doubt we're there yet.
> 
> Chris's patch seems eminently sensible to me.  Why should having separate
> interrupt stack depend on whether you're configured for 4K or 8K stacks?
> 
> Wasn't Andrea worried, a couple of months back, about nested interrupts
> overflowing the 4K interrupt stack?  He was trying to work out how to
> have an 8K interrupt stack even with the 4K task stack, proposed thread
> info at both top and bottom of stack; but his "current" still looked to
> me like it'd be significantly more costly than the present one.
> 
> I'm all for Chris's patch.

I have no problem with 8K interrupt stacks - they're static, and per CPU,
so I doubt anyone cares ... 

But 8K task stacks + interrupt stacks seems to just encourage bloat to me.
And if you agree that we're going to 4K, I don't really see the point - 
if people are really hitting problems (I don't recall any actual reports)
then I'd prefer to see them fixed properly by poking the fat bloater with
a big pin.

M.


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