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Old 03-22-12, 07:56 PM   #1
maro
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Default performance issue (how to investigate?)

Hi,

this is not so much a bug report but the request for advice how I can investigte this further since I cannot find any information in the system logs.

The issue is that in Second Life I usually get around 20 fps in crowded places, but after a while the frame rate breaks down to 3 or so. I can reset it by toggling the window manager (eg. compositing on/off) but after a while it repeats.

Hardware: core i7 860, Palit GTX 560 Ti, 8 GB RAM
Software: Slackware 64 current, Kernel 3.2.11-ck1, Xorg 1.9.5, nvidia 295.20, Twinview

Observations and variation of parameters:

1. when it happens, the complete GUI is affected, reacting to clicks very slowly everywhere, including outside the viewer window

2. background apps run fine, so cpu scheduling is not the issue

3. happens with or without Twinview

4. tried 6 versions of 2 different viewers: all are affected, but it seems the firestorm viewer triggers the issue more frequently than the SL viewer

5. frame rate picks up when reducing graphical settings, but later goes down again. seems most sensitive to shader settings.

6. happens with different window managers (kde, xfce) with and without compositing

7. gpu and cpu temperatures are fine when it happens, cpu load is below maximum (eg. 200% with 8 logical cores available).

Since it looks like there is one particular resource running out I'd like to test this hypothesis. Question is: how can i monitor gpu resources?

Thanks and regards,

Martin

PS: gonna try the 295.33 driver next, but the changelog didn't mention anything relating to this issue.
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Old 03-24-12, 06:48 AM   #2
maro
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Default Re: performance issue (how to investigate?)

just a quick update: i am currently experimenting with reducing the texture memory parameter inside the application. it used to be set to the maximum of 512 MB which seemed OK since the card apparently has 1024 MB GDDR5.
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Old 03-29-12, 03:26 PM   #3
maro
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Default Re: performance issue (how to investigate?)

well, whenever I relax a setting (texture memory, atmospheric shaders) I just manage to push the boundary, but eventually the frame rate collapses. I can fix it temporarily by toggling the composition flag of the window manager, but after a while it happens again.

Any idea how to investigate further?
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Old 04-06-12, 03:07 AM   #4
maro
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Default Re: performance issue (how to investigate?)

still no progress. since there are no traces in the logs, are there any other key figures I could monitor? in debugfs maybe?
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Old 04-09-12, 05:03 AM   #5
maro
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Default Re: performance issue (how to investigate?)

is there somthing like /proc/meminfo for gpu memory?
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Old 04-09-12, 07:40 AM   #6
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Default Re: performance issue (how to investigate?)

Try

Code:
nvidia-smi -q -d MEMORY
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Old 04-10-12, 06:51 PM   #7
maro
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Default Re: performance issue (how to investigate?)

Thanks, that's a cool tool. Using the -l flag I am able to gain additional insight in my problem. i caught it today, and it appears it is triggered when i use a composition window manager and the gpu memory usage reaches 99%. When switching off compositing, the memory consumption immediately drops and the frame rates recover. When they get up to 99% the system seems to handle the situation much better. it may get a bit slower, but nothing like in the compositing case. on the down side i had viewer crashes in the past without compositing.

So who do i talk to now with these findings? the driver people (nvidia)? the window manager people (xfce, kde, ...)? the viewer people (sl viewer, phoenix firestorm, ...)? the gaphics stack people (xorg, libs, kernel)?
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