Did my CPU or my graphics card bottleneck this mission?

[latearrival]

G'day!

 

I was pretty happy to find that my trusty old LGA775 system could run all the training missions at 35fps+. Then I tried this mission, kindly shared by JEFX, which starts at a busy airbase:

 

Here Poko and Peter, my little atmospheric ramp start.

you can get it here:

[ATTACH]50268[/ATTACH]

 

It is a very simple mission and a quite easy one, but I made it in order to show some friends the beauty of the simulator.

 

Blimey! The sim ran so slowly, stuttering and freezing and then running at between 1 and 8fps, that I couldn't even get my engines started!

 

Sooooo, do you guys think that this is likely to be my cpu or graphics card bottlenecking me here?

 

Given I'm running a single screen at a lowly 1024x1280 with only 'textures' at high, everything else on medium or low, I'm thinking it's my CPU. What do you think?

[Pyroflash]

Lots of AI traffic can definitely kill your performance on a low end CPU. on the other hand, looking at a large amount of units can also put strain on the GPU.

 

Try looking down in your cockpit, and tell me if it still lags. If it does, then it is probably your CPU. If the lag miraculously goes away, then it was probably your GPU causing all the troubles. Alternatively, as soon as you load in, F11 to another air base. If your lag goes away, same thing.

 

Also, make sure bushes/clutter is at zero meters, and turn your textures down to medium. IF it doesn't fix the problems, it sure will help. To be honest though, the GTX 260 is a rather low end card for today, and I would recommend a complete overhaul of your entire system(Look at my specs though and imagine now that I do this every year, I fully realize that a lot of people can't make that sort of monetary commitment to their computers, I myself don't know why I bother year after year).

Edited April 14, 2011 by Pyroflash

[latearrival]

Thanks Pyroflash.

 

Clutter was already at zero but I lowered Textures to Medium (and MSAA from 8 to 4 while I was at it) and the freezes/stuttering vanished. Great!

 

Looking down in the cockpit (or at the left or right panels), I get about 30fps. Looking vertically up, 40fps. Outside left and outside front (less action going on there), about 10-15fps. Outside right (lots going on), around 8-10fps.

 

From what you're saying it sounds like more of a GPU bottleneck than a CPU.

 

Unfortunately, the GPU upgrade will have to wait for the piggybank to fill up again. I only just ordered an i5 2500K...

[rextar]

I have the gtx260 too late, its time for an upgrade myself!

One thing are u getting your i5 from uk?

If so where? Cheers rextar.

[latearrival]

I have the gtx260 too late, its time for an upgrade myself!

One thing are u getting your i5 from uk?

If so where? Cheers rextar.

 

Sorry, but not the UK rextar - Australia

[aceflier]

Im geting simalar on the track he posted but with SLI on 260's im getting about 12-18fps lookin at all that takeoff stuff. 7-10 fps with single card. And this is with a modified terrain.lua file for medium settings to make visibility further out for cities and such and my trees are at 6000. 1920x1080 4XAA HDR on water low.

 

have a q6700 cpu at 3.5ghz pretty close to your spec.

 

Looks to be gpu limited to me. Seems to nearly max out my gpu ram 890mb usage both cards at 60-90% gpu usage.

 

I'll be going 2600k and gtx560 2gb sli in the next few weeks I'll post results for comparison.

 

 

 

 

SLI OFF/ON

Edited April 19, 2011 by aceflier

[Prophet4no1]

FYI, two 560's in SLI is still only 1GB memory. All the info is put on both cards. So the memory is not shared at all. Unless you have a multiscreen setup with each screen supporting resolutions past HD, 1-1.5GB is all you really need.

[Moa]

What speed is your RAM running at? With lots of units that can be a bottleneck. Part of the reason a new CPU would seem faster is that you would also be doing a motherboard and RAM upgrade. If your bus changes transfer from 6400 or 8500 MB/s to 17066 MB/s it often allows your CPU and GPU to run at full speed.

 

That's why your trusty old Q6700 can mostly handle it, it is probably idling while waiting for stuff to come across the bus. Your Radeon is pretty powerful and probably also idle half the time waiting for data to come to it.

 

You can tell what your CPU is doing using the free CPUZ program. Run it and see what the cores are up to. If one of them is pegged at 100% then there is your bottleneck. Most likely it won't be that.

 

Then get the free GPUZ program and see what your GPU is doing. If it is at 100% then that is the bottleneck. Most likely it won't be that.

 

If neither your CPU or GPU are running at 100% then the chances are that your bus transfer rate (RAM speed and size [how much you can buffer]) is the culprit. If you upgrade you can spend less on the CPU (although the i7 2600k is relatively cheap) and divert any savings into the fastest RAM and motherboard to support that RAM. Later, you can upgrade the CPU when you have more funds (it is cheaper to upgrade the CPU after getting a good mobo and RAM then get an expensive CPU and be bottlenecked by mobo and RAM or pay to upgrade both later).

 

Don't forget to post to this thread telling us of your experience. Good luck.

[Kuky]

It's easy to tell if the GPU is bottleneck as GPU-Z will show utilization accross 1 GPU core... with multi core CPU's where load of the game is spread accross multiple cores this is not easy to tell.

 

I think I got around 10-20 fps in that mission roughly with i7 950 @ 4GHz, 12GB DDR3 and and HD 5870 running 1920x1800 resolution... there are lot of high poly models very close and I of the option it's putting bottleneck on the GPU first.

 

EDIT: just thought about that maybe it's possible to manually change affinity for DCS executable to single core then test again... I'll try it next time I get my PC running (currently apart as I did HDD upgrade for my work PC to SSD and now I need to get another one for my gaming PC)

Edited April 19, 2011 by Kuky

[Moa]

Polygon counts are usually tiny in comparison to pixel counts on textures (especially when multi-textured is being used). Textures eat bus bandwidth like there is 'no tomorrow'. So textures dominate bus transfer.

 

Polygons count for vertex operations which are also small compared to per-pixel operations (especially when anti-aliasing, anisotropic filtering or occlusion calculations are being performed). For each vertex in your polygon your shader will interpolate a lot of 'fragments' to produce one screen-space pixel. So texture interpolation, projection, lighting and filtering also dominate GPU processing operations (hence Il-2 CoD is struggling with its screen space ambient occlusion operating on per-pixel operations using textures, normal maps and materials).

 

Will be very interesting to see your numbers Kuky when you find time to make that run with constant CPU affinity.

Edited April 19, 2011 by Moa

[Cibit]

I have the gtx260 too late, its time for an upgrade myself!

One thing are u getting your i5 from uk?

If so where? Cheers rextar.

 

Try Scan computers, no hesitation recommending them:thumbup:

[latearrival]

Thanks for all your thoughts everyone. I decided that it was probably about time I took the plunge and upgrade my PC anyway - I'm moving to an i5 2500k + GTX 560, and staying at 1024x1280, and so I'm hoping for a bit of an increase in FPS. This mission will be a good test.

 

(When I first bought this sim, I didn't realise I was going to haemorrhage money! First the Track IR, then the HOTAS, then the pedals, then VAC, then the PC upgrade, whatever next?!)

[aceflier]

FYI, two 560's in SLI is still only 1GB memory. All the info is put on both cards. So the memory is not shared at all. Unless you have a multiscreen setup with each screen supporting resolutions past HD, 1-1.5GB is all you really need.

 

You didnt read my post correctly.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16814261099

 

2X560's 2GB's that 2GB per card and yes I'm aware that the 2gb is shared with each card the reason I'm going 2gb cards.

Edited April 19, 2011 by aceflier