Messages in this thread |  | | Date | Wed, 11 Oct 2000 17:42:53 +0100 (BST) | From | Tigran Aivazian <> | Subject | Re: 36 bit MTRRs, Re: test10-pre1 problems on 4-way SuperServer8050 |
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On Wed, 11 Oct 2000, Boszormenyi Zoltan wrote:
> On Wed, 11 Oct 2000, Tigran Aivazian wrote: > > I will continue to narrow down by removing some things (like mtrr) from > > the equation. Rik, the problem is that when one enables PAE (or just > > highmem-4G) support on a 4-way 6G RAM machine becomes 38-40 times slower. > > Will you please try this patch? This is almost the same as I > sent to you before, it is just against 2.4.0-test10-pre1 and > it lacks the corrections to e.g. the frame buffer drivers.
Hi Zoltan,
I have tried your patch and although it works:
# cat /proc/mtrr reg00: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1 reg01: base=0x00100000000 ( 4096MB), size= 2048MB: write-back, count=1 reg02: base=0xfc000000 (4032MB), size= 64MB: uncachable, count=1
unfortunately, it doesn't solve the problem. The machine is still unbearably slow (up to 40x slower!) and one of the eepro100 interfaces is still not working.
Another interesting idea was suggested by Mark Hemment - to switch
memlist_add_head() -> memlist_add_tail()
in expand()/__free_pages_ok() (see mm/page_alloc.c) and it did make a difference -- both eepro100 started to work fine but the machine remained just as slow as before.
So, the problem is complex but I am told that Rik and others are aware that at present there is no working support for highmem. Strangely, my desktop dual PIII550 with 1G RAM works just fine with highmem... nice and fast, no problems whatsoever and it is filled up with all kinds of devices, from soundcard to bttv848, 3dfx, eepro100, ne2k, 8139 etc etc. Everything just works.
Regards, Tigran
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