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To: Juli Mallett <jmallett@FreeBSD.org>
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On Jan 26, 2014, at 9:04 AM, Juli Mallett wrote:

> On Sun, Jan 26, 2014 at 7:07 AM, Jan Bramkamp <crest@rlwinm.de> wrote:
>>=20
>> Would increasing KSTACK_PAGES from two to three or four help? What =
are
>> the trade-offs involved in choosing KSTACK_PAGES for something like =
the
>> EdgeMax Lite?
>=20
>=20
> That's exactly what needs to happen in all 64-bit MIPS kernels.  =
Unlike
> some other architectures,  KSTACK_PAGES cannot simply be increased,
> however.  All of the code which handles loading the kernel stack and
> keeping it mapped, etc., assumes that it takes up exactly one TLB =
entry,
> i.e. 2 pages.  One could simply double KSTACK_PAGES for 64-bit builds =
and
> modify the code to support the case of 2 or 4 pages, which would keep =
the
> code as gross as it is today and not buy much flexibility, but might =
be
> worthwhile as a short-term fix.  Being able to support arbitrary =
values of
> KSTACK_PAGES (or at least arbitrary multiples of 2 up to the maximum =
number
> of wired TLB entries times 2) would be better.

I hacked together a kludge that quadrupled this by going to the next =
larger page size for stack pages in the TLB, but hit something ugly when =
I did that... But I've lost that code, so maybe I should try again to =
see if I'm more clever the second time.

This is one of the things that makes it hard to have a nice native build =
server on mips64...

Warner