Re: [discuss] Re: x86_64: 2.6.14-rc4 swiotlb broken

[Alex Williamson <alex.williamson@hp.com>]

On Tue, 2005-10-18 at 12:54 -0700, Ravikiran G Thirumalai wrote:
> On Tue, Oct 18, 2005 at 08:50:18AM -0700, Linus Torvalds wrote:
> > 
> > 
> > On Tue, 18 Oct 2005, Linus Torvalds wrote:
> > > 
> > > I vote for this one, assuming everybody who can test is happy.
> > 
> > Of course, just after sending the patch I noticed that there was a new 
> > version, even simpler. Can people test that one?
> > 
> 
> This version should work for everyone.  It falls back to the old 2.6.13
> behaviour when it does not find suitable memory from any of the nodes.
> 
> Yasunori-san, Alex, can you confirm.  (Please use stock 2.6.14)

   Oops, I used 2.6.14-rc4-mm1, I'll retest.  However, this does work on
the Superdome.  Not because of the iterating over the nodes code, but
because of the call to alloc_bootmem_low_pages() fallback case.  Adding
a printk(), I get this:

Node 0: 0xe000074104e6b200
Node 1: 0xe000082080723000
Node 2: 0xe000000101532000  *Note this is the interleaved memory node
Placing software IO TLB between 0x4cdc000 - 0x8cdc000

Looking at the memory map of the system, I see these major ranges:

Node 2:
0x00000000000 - 0x0007ffdefff (~2GB)
0x00100000000 - 0x0017fffffff (2GB)
0x04080000000 - 0x040f0000000 (2GB)
Node 0:
0x74100000000 - 0x741fbbfffff (~4GB)
Node 1:
0x82080000000 - 0x820fb453fff (~2GB)

So, it looks like we're iterating over the nodes, but
alloc_bootmem_node() isn't even guaranteed to try to get memory from the
low memory on that node.  Thanks,

	Alex