From: William Lee Irwin III <wli@holomorphy.com>
To: "Martin J. Bligh" <mbligh@aracnet.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@digeo.com>,
haveblue@us.ibm.com
Subject: Re: Overhead of highpte
Date: Wed, 2 Jul 2003 16:15:02 -0700 [thread overview]
Message-ID: <20030702231502.GJ26348@holomorphy.com> (raw)
In-Reply-To: <574790000.1057186404@flay>
On Wed, Jul 02, 2003 at 03:53:24PM -0700, Martin J. Bligh wrote:
> Some people were saying they couldn't see an overhead with highpte.
> Seems pretty obvious to me still. It should help *more* on the NUMA
> box, as PTEs become node-local.
> The kmap_atomic is, of course, perfectly understandable. The increase
> in the rmap functions is a bit of a mystery to me.
The rmap functions perform kmap_atomic() internally while traversing
pte_chains and so will take various additional TLB misses and incur
various bits of computational expense with i386's kmap_atomic() semantics.
The observations I made were in combination with both highpmd and an as
of yet unmerged full 3-level pagetable cacheing patch.
-- wli
next prev parent reply other threads:[~2003-07-02 23:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-02 22:53 Overhead of highpte Martin J. Bligh
2003-07-02 23:15 ` William Lee Irwin III [this message]
2003-07-03 0:02 ` William Lee Irwin III
2003-07-04 2:34 ` Dave Hansen
2003-07-04 2:46 ` Martin J. Bligh
2003-07-04 2:54 ` Dave Hansen
2003-07-04 3:53 ` Overhead of highpte (or not :) Dave Hansen
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