RE: large page patch

[Seth, Rohit]

There is typo in Andrew's mail.  It is not 256K, but it is 256MB.

-----Original Message-----
From: David S. Miller [mailto:[e-mail]]
Sent: Thursday, August 01, 2002 6:20 PM
To: [e-mail]
Cc: [e-mail]; [e-mail];
[e-mail]; [e-mail]; [e-mail]
Subject: Re: large page patch

   From: Andrew Morton <[e-mail]>
   Date: Thu, 01 Aug 2002 18:26:40 -0700

   "David S. Miller" wrote:
   > This is probably done to increase the likelyhood that 4MB page orders
   > are available.  If we collapse 4MB pages deeper, they are less likely
   > to be broken up because smaller orders would be selected first.
   
   This is leakage from ia64, which supports up to 256k pages.

Ummm, 4MB > 256K and even with a 4K PAGE_SIZE MAX_ORDER coalesces
up to 4MB already :-)
   
   Apparently a page-table based representation could not be used by PPC.
   
The page-table is just an abstraction, there is no reason dummy
"large" ptes could not be used which are just ignored by the HW TLB
reload code.