Re: [PATCH] small sym-2 fix

Gérard Roudier
2001-11-15T20:52:58Z

On Thu, 15 Nov 2001, David S. Miller wrote:

> From: Gérard Roudier <groudier@free.fr>
> Date: Thu, 15 Nov 2001 17:27:38 +0100 (CET)
>
> The driver should not need more than 4096 bytes for a single allocation.
>
> If platform is 64-bit and PAGE_SIZE < 8K, yes it will.
> And ppc64 fits this criteria.

Btw, I didn't see any ppc64 stuff in linux kernel. As a result this
platform is still in the unsupported status. :-)

Indeed a 4K page on a 64 bit machine looks very suboptimal. Note that it
is also way too small for 32 bits machines with hundreds of megabytes of
memory. I am wondering about the reasons that made us keep with so small a
page size. As you know earlier BSDs used 2K on Vaxen that as you also know
had (have?) a physical PAGE_SIZE of 512 bytes.

About the sym-2 driver, it may well be some pointers that make it need
more than 4K allocation on 64 bit machines.

I will try to make it fit a page size max allocation even on such weird
configuration, since I do consider as high^H^H^H^Hslightly broken any
piece of software that requires more that 1 PAGE of physically contiguous
allocation. :-) :-) :-)

To be serious, the right fix is to have some logical page be some power of
two of the physical page when the physical page is too small. Can we hope
Linux-2.5 to allow this?

Gérard.