RE: large page patch

Seth, Rohit (
Thu, 1 Aug 2002 18:34:04 -0700

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

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

From: Andrew Morton <>
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.
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