From: Christoph Lameter <clameter@sgi.com>
To: Andi Kleen <ak@suse.de>
Cc: linux-mm@kvack.org, haveblue@us.ibm.com
Subject: Re: One idea to free up page flags on NUMA
Date: Sun, 24 Sep 2006 20:46:37 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0609242041210.19943@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <200609250504.58427.ak@suse.de>
On Mon, 25 Sep 2006, Andi Kleen wrote:
> > Right could be in highmem and thus would free up around 20 Megabytes of
> > low memory.
> But won't the vmemmap need more than the 20MB?
It will need the same as the regular mmap + one / two page table pages
pointing to the huge pages of the virtual memmap. So if one goes from
regular mmap to virtual mmap one pays with a few page table pages and the
need for additional TLBs for lookup. But one can remove the memmap
entirely from the low memory area.
If we upgrade sparse to be able to use vmemmap then we trade the
existing sparse structures against the few page table pages plus the
TLB overhead.
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next prev parent reply other threads:[~2006-09-25 3:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-23 3:02 Christoph Lameter
2006-09-23 16:04 ` Andi Kleen
2006-09-23 16:39 ` Christoph Lameter
2006-09-23 18:43 ` Andi Kleen
2006-09-24 1:57 ` Christoph Lameter
2006-09-24 7:24 ` Andi Kleen
2006-09-25 0:31 ` Christoph Lameter
2006-09-25 3:04 ` Andi Kleen
2006-09-25 3:46 ` Christoph Lameter [this message]
2006-09-23 19:24 ` Dave Hansen
2006-09-24 1:56 ` Christoph Lameter
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