Re: New slab allocator SLUB

[David Miller <davem@davemloft.net>]

From: Christoph Lameter <clameter@sgi.com>
Date: Thu, 10 May 2007 15:21:52 -0700 (PDT)

> On Thu, 10 May 2007, David Miller wrote:
> 
> > What SLAB allows you to do is define LARGE_ALLOCS but not necessarily
> > set MAX_ORDER large enough for the largest kmalloc SLAB.  SLAB would
> > ignore the kmalloc cache creation failures for these largest ones that
> > are over MAX_ORDER.
> 
> Hmmm... How about limiting KMALLOC_SHIFT_HIGH to max order?

That should definitely do the trick too:

Signed-off-by: David S. Miller <davem@davemloft.net>

I just confirmed that I don't actually need LARGE_ALLOCS on sparc64.
I think I needed them for some reason back when I used kmalloc() to
allocate the per-address-space TLB miss hash tables.

I think the issue was that for Niagara and later really huge TLB
hash table sizes are allowed, and I wanted to experiment with those
and the sizes were large enough to require LARGE_ALLOCS.  But now
I use SLAB for this and I cap the size at the pre-Niagara limit
of 1MB because larger sizes showed no performance gains.