Re: [PATCH 00/07][RFC] i386: NUMA emulation
From: Martin J. Bligh
Date: Mon Oct 03 2005 - 10:25:59 EST
--David Lang <david.lang@xxxxxxxxxxxxxxxxxx> wrote (on Monday, October 03, 2005 08:13:09 -0700):
> On Mon, 3 Oct 2005, Martin J. Bligh wrote:
>> --David Lang <david.lang@xxxxxxxxxxxxxxxxxx> wrote (on Monday, October 03, 2005 08:03:44 -0700):
>>> On Mon, 3 Oct 2005, Martin J. Bligh wrote:
>>>> But that's not the same at all! ;-) PAE memory is the same speed as
>>>> the other stuff. You just have a 3rd level of pagetables for everything.
>>>> One could (correctly) argue it made *all* memory slower, but it does so
>>>> in a uniform fashion.
>>> is it? I've seen during the memory self-test at boot that machines slow down noticably as they pass the 4G mark.
>> Not noticed that, and I can't see why it should be the case in general,
>> though I suppose some machines might be odd. Got any numbers?
> just the fact that the system boot memory test takes 3-4 times as long with 8G or ram then with 4G of ram. I then boot a 64 bit kernel on the system and never use PAE mode again :-)
> if you can point me at a utility that will test the speed of the memory in different chunks I'll do some testing on the Opteron systems I have available. unfortunantly I don't have any Xeon systems to test this on.
Mmm. 64-bit uniproc systems, with > 4GB of RAM, running a 32 bit kernel
don't really strike me as a huge market segment ;-)
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