RE: [RFC] 4-level page table directories.

From: Luck, Tony <>
Date: 2005-11-05 04:58:51
>It turns out that we have measurable performance regression with
>4-level page table running industry database benchmark, the penalty
>is ~0.2% (I thought the number would be smaller than 0.2%, but ...).
>Our resolution with this workload is typically 0.05%.

That makes it tough to make 4-level the default.  If there were a
lot more users that needed 4-level, I might tell Ken he'd have to
just live with it ... but this is only needed for a few HPC jobs
on very, very high end machines.

I'll put the patches into the test tree as they are (with 4-level
as the default) so that we'll get some test exposure in -mm.  But
if they move into the base it will be with 3-level as the default.

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Received on Sat Nov 05 04:59:28 2005

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