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rafal_lewczuk
Journeyman III

Ubuntu 8.04/amd64 instability

Where can I submit bug reports ?

Hi,

I'm not sure it is <<Stream>> question  but as the problem does appear only when trying amdbrook demos, I'm posting it here. Also, question to QA folks: there are so many people running Ubuntu on this forum, would you like to add ubuntu box to your testing fleet ?

I've bought a HD3870 (not X2) card to learn something about GPGPU and got into problems right after installing it. Finally  I've got amdbrook/amdcal demos working after a bunch of workarounds but some are still crashing my system. floyd_warshall_d for example. Graphics itself seems to work well albeit I didn't test it extensively. Help. Details below:

My machine: Q6600+8GB RAM, PCI remap option turned on (not tested turning it off though - but I'll do it ASAP and post results). Gigabyte HD 3870 card.

 

Workaround 1: changed MTRR settings due to fglrx crashing my system right after starting X (problem with fglrx appearing machines with >= 3GB RAM):

# cat /proc/mtrr

reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
reg03: base=0x100000000 (4096MB), size=4096MB: write-back, count=1
reg04: base=0x200000000 (8192MB), size= 512MB: write-back, count=1
reg05: base=0x220000000 (8704MB), size= 256MB: write-back, count=1

Note that I've left a hole between 3328MB and 4096MB. I'm not sure what shall I put here. write-combining ? nocache ?

Workaround 2:  # export LIBXCB_ALLOW_SLOPPY_LOCK=true

Workaround 3: removed splash from kernel boot parameters - to prevent switch from X to text crashing my machine;

Workaround 4: agp=off boot parameter (but I'm not sure it is needed anymore - it worked with my previous mobo where issue with PCI memory remapping caused panic during boot).

 

Regards,

rle

 

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3 Replies

Hi rle,

Let me see if I can get Ubuntu testing and support added seeing as there are enough people using Ubuntu.

Michael.
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Hi,

More details.

1. Turning off [PCI remap] feature does not make things better nor worse (except for enforcing change of MTRR settings accordingly);

2. Removinng agp=off does not change anything.

3. List of demos crashing my system: domain, double_precision_simple_matmult_d, image_filter_d, indexof, indexof_d, mandelbrot, prefix_sum, simple_matmult.

Please note that double_precision_optimized_matmult_d works correctly while double_precision_simple_matmult_d crashes.

4. Demos on list always crash my system, demos not on this list do not. I've not tested it very extensively, however - repeated few picked crashing programs (just to see yet another freeze) and run one or two non-crashing programs in a loop (plus repeated few other randomly picked to see them working again).

One more suggestion: adding a 64-bit box with >4GB RAM would be also nice - as RAM is so cheap today - I suppose 8GB will not be so uncommon among number crunching folks.

 

 

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Hi,

Ok, I've got what was going on.

It was propably hardware fault. I've returned that card back to the shop and bought 4850 instead. It is not officially supported but it works at least for me

Sorry for asserting false alerts.

Regards,

rle

 

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