Re: High Mem Options

William Lee Irwin III (wli@holomorphy.com)
Wed, 5 Mar 2003 12:58:49 -0800


On Wed, 05 Mar 2003 04:26:54 PST, William Lee Irwin III wrote:
>> Yes, the additional level of pagetables slows things down quite a bit.

On Wed, Mar 05, 2003 at 12:31:03PM -0800, Gerrit Huizenga wrote:
> Bill, do you hvae measures for this? I seem to remember PTX's impact
> of PAE36 as being about 3-5% depending on workload. Janet did one test
> sometime back with DB2 that showed a net of no difference on TPC-H (PAE
> slows things down, less memory pressure speeds things up) but Badari
> just repeated with 2.5.62 or 2.5.63 and saw a larger degradation.
> I'm wondering if some hardware is not getting correctly configured at
> boot with with respect to MTRR's, perhaps... I really wouldn't expect
> a 10% impact from PAE and I don't have any consistent Linux measurements
> to validate or invalidate that much impact.

Unfortunately the number of ca. 10% I got from you. I think badari's
done some $BENCHMARK_THAT_CANNOT_BE_NAMED things recently that were
consistent with the handwavy estimate but AIUI they were not intended
to measure the effect etc. etc.

-- wli
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/