Mac Pro Stress Test

Discussion in 'Mac Pro' started by Mr.PS, Feb 14, 2008.

  1. Mr.PS macrumors 6502a

    Jan 8, 2008
    What's a good way to stress test? I opened up 5 1080p HD demo's in quicktime. After the 3rd or 4th I started to get choppy playback. This is normal I assume, since HD playback is hitting the gpu hard, no the processor or ram.

    Can anyone here play 5 1080p trailers simultaneously?
  2. Pressure macrumors 68040


    May 30, 2006
    What you are seeing are probably the limitation of your harddrive and not the other hardware.

    And just so we are clear, you mean compressed High Definition content ;)
  3. Mr.PS thread starter macrumors 6502a

    Jan 8, 2008
    It did not seem to be using any HDD i/o during the playback. It was streamed since they do not allow you to download the content. My HDD throughput is really good, especially since it's a stripped array.
  4. 4God macrumors 68020


    Apr 5, 2005
    My Mac
    Then it most likely was your internet connection bottlenecking.
  5. martinlk macrumors member


    Jun 20, 2005
    Aalborg, Denmark
    Actually, HD playback puts a lot of strain on the CPU, not the GPU.
  6. Mr.PS thread starter macrumors 6502a

    Jan 8, 2008
    Not the case either, the videos were fully downloaded, plus I can download up to 3mb/sec. CPU usage was around 32%.
  7. benpatient macrumors 68000

    Nov 4, 2003
    a good stress test for something with 8 cores needs to be doing a variety of things simultaneously.

    if you were using downloaded 1080p content, and running more than one at a time, then you were straining your hard drives, almost certainly.

    you said they were not using hard drive i/o during playback, but they had to be, unless the clips were completely loaded into the RAM. graphics processing power doesn't come into play very much on a Mac because OS X doesn't utilize the onboard HD video processing components of the latest graphics cards. take a look at the video quality from DVD player to see what I mean, then compare that to a PC with a PureVideo-enabled NVidia GPU in it...embarrassing.

    Anyway, a RAID 0 array of 2 modern 7200 drives should be able to handle a couple of compressed HD streams with no lag. 5 or 6 is pushing it, unless they are buffered beforehand into the RAM.

    The 32% CPU usage you reported is probably 32% of the total 8 cores, depending on the utility you're using to report that usage percentage.

    that would equal 2.5 cores at 100% utilization. If the application you're using to play the videos isn't able to run separate CPU threads for each open window, then that would be a likely utilization scenario...a video player that's 2-core capable, running two cores at 100%, and the other 50% usage is from the rest of your system, compensating. I'm not sure how many cores quicktime will use at once.

    can you give more details on your set-up? how much ram?
  8. ErikAndre macrumors 6502a


    Nov 14, 2007
    So it is on your hard drive then (perhaps an internet temp location)... it very well could be a HDD limitation.
  9. Mr.PS thread starter macrumors 6502a

    Jan 8, 2008
    I'm running 6gb of ram. The videos are "downloaded" in the sense that they're streamed from quicktime and held somewhere until you close down quicktime. The site won't let you right click save as, if you know what I mean. I was using activity monitor to determine if HDD i/o was being used, and it wasn't - that is according to activity monitor. Around 2.5gb of ram was used and 32% of all cores. So like you said, 2 cores at 100% pretty much. Thanks for explaining it a bit better, I was worried that my Mac Pro had something wrong with it.

    It could, I won't argue, but activity monitor shows no disk i/o. So I'm not sure.
  10. BryanLyle macrumors 6502a


    Aug 2, 2005
    I ripped a dvd and ran it through the latest version of visual hub with the Go nuts setting. Activity monitor showed all 8 cores in heavy use. A 2 hour movie took 30 minutes to encode to an Apple TV 5.1 format. I would say that is pretty good :)
  11. benpatient macrumors 68000

    Nov 4, 2003
    while you're playing 2 hd streams, run a bunch of photoshop filters with an Action on a large file in CMYK color...then turn on expose.

    that will get your CPU utilization up a bit higher, so you can verify that they work!

    there is also a terminal command you can run that will basically just cause one core to process gibberish at 100% can open 7 of those and see how responsive your machine is...that's a single core mac pro, at that HD drain, little-to-no RAM usage, almost no i/o. just 700% CPU utilization. It should be fun.
  12. gretafour macrumors regular

    Aug 26, 2006
    Rochester, NY
    CPU Stress Test

    I was just looking to do the same thing! Turns out someone wrote a nice little program that feeds a bunch of nonsensical mathematical calculations to the CPU as fast as it can do them. Result: 100% usage. You set it to run as many "instances" as your CPU has cores. So on my Core 2 Duo, I run two instances.

    It's called CPUTest 0.2. Works well for me! Hope this helps.

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