Thunderbolt Performance

The Eagle Ridge Thunderbolt controller is home to two Thunderbolt channels, each one is good for up to 10Gbps in either direction (up or downstream). That works out to be 20Gbps of bandwidth per channel or 40Gbps aggregate between the two. You can only send two channels worth of data down a single Thunderbolt cable, so there's no point to having more than two from a performance standpoint unless you have more than one port on your system.

If DisplayPort and PCIe traffic are indeed carried on separate channels, then the Thunderbolt Display by itself is eating up around 70% of the bandwidth of a single channel on its own (2560 x 1440 x 32bpp x 60Hz with 8b/10b encoding > 6.75Gbps). That leaves 10Gbps in each direction for PCIe traffic. If we look at our benchmarks from the previous section we see that we can hit just under 2Gbps with all of the auxiliary interfaces (GigE, FW800, USB2) running. Given our previous investigation with the Promise Pegasus we know that 8Gbps is feasible there as well. It's possible, that with everything running at once, we could actually run into bottlenecks with Thunderbolt.

To find out I ran a few tests. First I needed a baseline so I threw four SF-2281 SSDs into the Pegasus R6 chassis and configured them in a RAID-0 array. I ran a 2MB sequential read test (QD=16) and measured 909MB/s from the array. This value was obtained without the Thunderbolt Display connected, only the Pegasus R6.

Next I connected the Thunderbolt Display directly to my test MacBook Pro, and then connected the Pegasus to it. I repeated the test, this time getting 900MB/s. Thankfully the presence of the Thunderbolt Display doesn't seem to impact the max data rate I can get from the Pegasus.

For my third test I added a Gigabit Ethernet transfer from a file server to a local SSD using the GigE port on the display. During this test I was also playing back music using the Thunderbolt Display's internal audio codec and speakers. I re-ran the Pegasus test and got 855MB/s.

For my final test I re-ran the third test but added a FireWire 800 to USB 2.0 SSD transfer, both connected to the Thunderbolt Display. I also fired up the FaceTime HD camera on the display using Photo Booth and left it on during the test. The final performance score from the Pegasus was 817MB/s.

Apple Thunderbolt Display Performance

With everything running Thunderbolt performance took a 10% hit. Note that the standard Pegasus configuration isn't able to hit these data rates to begin with, so unless you've pulled out the 12TB of storage and stuck in your own SSDs you won't see any performance drop.

What this does tell me however is the ultra high end users that are looking to daisy chain multiple Thunderbolt storage boxes together may not want to do so. I only have a single Pegasus R6 on hand, but I'm guessing there will be significant performance drop off after the first box. Not that I'm complaining about being able to push nearly 1GB/s over a $49 cable from a notebook, I'm just trying to give a heads up to those who may have aspirations of even higher performance.

Testing the Pieces Display Testing - Color Quality & Uniformity
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  • doubledeej - Sunday, September 25, 2011 - link

    I have many friends that work in "broadcast" and all but one of them lust after the Apple displays because they've got this silly notion that they are the best out there. No matter how many charts, spec sheets, reviews, etc., I throw at them, they refuse to believe that a Dell, Eizo, or anybody else could produce a monitor that performs better, especially if said monitor happens to be less expensive. There are an awful lot of Apple Kool-Aid drinkers out there, and nowhere is it worse than with video "professionals." Reply
  • seapeople - Friday, September 23, 2011 - link

    My new Dell XPS 17 has an antiglare screen. Moderate progress? Reply
  • Dennis Travis - Friday, September 23, 2011 - link

    Excellent review Anand as always. You covered everything I was curious about and more. Thanks again! Reply
  • HHCosmin - Friday, September 23, 2011 - link

    want to say i just love your reviews Anand. i can tell you are passionate about what you do.
    this thing seems quite cool and it brings lots of help in cable clutter area. however i'm a pc guy and this is a mac. you talk about the future, and the possibilities. i've been thinking about this for some time now and getting really excited about the implications. i can see getting standard having monitors with thunderbolt and not much else to keep price down. link the display (through thunderbolt) cases that have sata ports and pciexpress ones. i call this a "slave box".

    to have:
    - laptop: slim, light, good autonomy (should be able to power this via display)
    - display with thunderbolt, with ability to extend and not much extra
    - a "slave-box" having psu, hdds, gpus and pciexpress slots for extras (no memory or cpu)

    you get:
    - use (and pay for) a single machine that you can carry around (with igp only)
    - have practically no cable clutter
    - get to feed power to the laptop through the monitor (when/if laptop maker standardize mobile bricks)
    - have extra gpu/storage/sound etc when you are at home/office
    - be able to upgrade the gpu
    Reply
  • willmo - Friday, September 23, 2011 - link

    Anand: I suspect that the Thunderbolt Display uses a Light Ridge controller, and the reason its DP output is not available for daisy-chaining is that it's used to drive the Thunderbolt Display's own panel. Reply
  • willmo - Friday, September 23, 2011 - link

    Never mind, I hadn't gotten to the dissection yet. I assume the part number on the Thunderbolt controller checks out as Eagle Ridge... Reply
  • Ryan Smith - Friday, September 23, 2011 - link

    Anand and I actually went back and forth on this. It's our belief that the display is being fed by LVDS, processed by some hereto unidentified controller on the logic board. You can see the ZIF cable connector on the following image, it's the gold colored component near the top-right: http://www.anandtech.com/Gallery/Album/1405#38 Reply
  • ermhmm - Friday, September 23, 2011 - link

    there is a product i'm not sure if its in production or whether you can use a GPU with it, but its similar to what you were talking about you can read about here. http://news.softpedia.com/news/Magma-Intros-PCI-Ex...

    as for gaming i'm in the UK and recently tried Onlive on my macbook and have to say i love the idea of cloud gaming solves the problem of expensive hardware for gaming.
    Reply
  • efeman - Friday, September 23, 2011 - link

    One small thing to point out: it looks like the wrong table was used in the "Testing the PIeces" section: it's listed as power consumption instead of something along the lines of transfer rates.

    I picked up the 4GB/128GB 11" Air a few days ago ($300 off!) for campus use; it does everything I need it to do in a great form factor. I was originally looking at a 14" unit, maybe a Lenovo E420s or T420s, but I haven't looked back. I have a self-built gaming desktop at home, yet the idea of a Thunderbolt future really intrigues me. While I don't ever see myself buying something like this display, I'm hoping to see cheaper storage solutions, and my fingers are crossed for external graphics support, as that's the only thing I'm missing on a unit like this.

    Excellent review, as usual. I don't know if a video review has been done before, but I enjoyed it. The main points of the article in an easily-digestible form for those times that I don't want to read through paragraphs. I hope we see them in every review :-)

    Off-topic: In case this post gets any attention, is there any chance the Macbook Air review can be updated with internal temperature data? I was disappointed to only see the surface and exhaust temperature info.
    Reply
  • eXces - Friday, September 23, 2011 - link

    love your video review! keep on excellent work! Reply

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