7 ms·

I know what you mean, but it has gotten a lot cheaper. There are sub-$1K 10G switches and consumer-ish onboard-10G motherboards. Probably, something popular ne

• JohnJamesRambo 8y ago
  Can you expand on that last sentence? I don’t understand it but it sounds interesting.
  • Firerouge 8y ago
    Fiber optic cables are too fragile for home use. If bent to any extreme the cable will be ruined. Hence only useful in homes with protected installations like a server enclosures.
    • NightlyDev 8y ago
      That's a myth. Fiberoptic cables are actually really robust.
      • StillBored 8y ago
        Well POF is, real glass still has bend diameter limitations, but most people aren't using single mode longer fiber runs that need glass. So, yes, all the common stuff is pretty flexible, because its plastic.
        • myself248 8y ago
          Yes and no. Even singlemode can be pretty flexible. Every manufacturer's product is different, but even 20 years ago, the singlemode we were installing could be wrapped around a Sharpie without damage (though it would lose a lot of light; that was an installation-only ability), and would happily tolerate something like twice that bend radius during operation. That being said, I've seen people do some horrific things with copper, and it tends to survive things it shouldn't. But if you treat glass even half as gently as copper wants to be treated, they'll both be fine. I think fiber gets a bad rep because large multi-strand cables have stiffeners to keep the jacket from kinking, and people assume the individual strands are similarly stiff. They really aren't.
          • sathackr 8y ago
            Just a couple of weeks ago[1]. The fiber wasn't run properly and got pinched between some innerduct and the conduit edge. Had 20+db of loss while it was pinched, but after unpinching it and massaging the kink out, it went right back to normal. [1] https://imgur.com/a/bHX6eRJ https://imgur.com/a/bHX6eRJ
    • olefoo 8y ago
      For the lengths in use in home installations ( n < 1km ) plastic cables with a much greater modulus of elasticity can be used since the greater signal attenuation won't be a factor.
      • exikyut 8y ago
        Are you saying there are plastic-based alternatives to optical fiber cables? Wow. What are these actually called, and what do I look for?
        • rdl 8y ago
          Polymer Optical Fiber (POF). Very common and essentially the standard in non-telco/non-IT use of fiber data networks (process control, vehicles, etc). I’ve seen studies of using them for gigabit or better computer networking, but I don’t think it is common yet. What people mostly mean here is multimode vs single mode glass fiber, though.
          • detaro 8y ago
            A company called Fuba makes Gigabit POF products which got quite favorable reviews. They are "media converter" type products for single runs though and not cheap, so no GBICs or switches with many ports.
    • StillBored 8y ago
      Which is silly as most people don't have houses that need 200M runs much less the 50M that is possible with 10GbaseT over cat5e. Why spend money on SFP's and optical cables, when you can just pick up cheap 10GbaseT hardware?
      • tssva 8y ago
        The 10GBASE-T doesn't support Cat5e cabling. It supports a distance of up to 55m on Cat6 and 100m on CAT6a. 10GBASE-T is showing up in more and more small business targeted equipment but I think more likely 2.5GBASE-T and 5GBASE-T will make it to consumer home equipment instead of 10GBASE-T. 2.5GBASE-T supports a distance of up to 100m on CAT5e. 5GBASE-T supports up to 100m on CAT6 and may operate on some Cat5e infrastructure. Additionally they both support PoE which 10GBASE-T does not.
        • virtuallynathan 8y ago
          10GBase-T certainly can work on cat5e, I run it over 10-20m at home.
          • mseebach 8y ago
            Works != supports
            • namibj 8y ago
              Can you explain why you need that much official blessing from the manufacturer to use it? If it doesn't work, you send it back?
              • mseebach 8y ago
                Well, if you bought something that says on the box that it doesn't do X, you generally don't get to send it back because it doesn't do X. Some consumer outlets may let you do this as a courtesy, but it's not ubiquitous and certainly not if you're buying from trade suppliers. Also, for a 10-20m run, the price difference is literally in the single figures. The effort alone to send something back is (should be) worth more to you than that.
• benaadams 8y ago
  > Probably, something popular needs building that demands 10G-in-the-home to use, in order to get volume up so pricing can come down a bit. HDMI 2.0 for 4K is 14.4 Gbit/s HDMI 2.1 for 8K is 42.7 Gbit/s
  • exikyut 8y ago
    ...how cheap is HDMI capture? Receiving non-visual data from the GPU has the interesting property that the shaders and video RAM are generally kind of very close to the HDMI port, so I could potentially be "sending" the result of running a shader on data in video RAM. Something something using VRAM for caching...? I've been meaning to figure out how to capture HDMI, at line speed, for a while. My current thinking is to use a PCIe FPGA capable of bus-master DMA, a horribly-hacked-apart kernel that doesn't touch a few GB of RAM, and a kernel driver to "chase" after the gigantic ring buffer the FPGA copies into. Hmm, I probably wouldn't be able to copy at HDMI 2.1 line rate. Unless there are very very scary FPGA contraptions that use TWO PCI-e slots? :D:D [EDIT: I now realize this would need two PCI-e root complexes. Woops]
    • pjc50 8y ago
      HDMI capture devices are still in the >$100 range, it seems. That usually runs it straight into an MPEG encoder though. I believe any FPGA with a decent PCIe implementation should be able to bus-master, and if you set up the drivers properly you don't have to do anything with the kernel, it'll just allocate a block of transfer RAM for you. You can use multiple PCIe lanes easily? If you need more than an x16 slot I'd be very surprised.
      • namibj 8y ago
        One PCIe3 x16 slot can handle about 120 Gbit/s full duplex.
      • exikyut 8y ago
        > HDMI capture devices are still in the >$100 range, it seems. That usually runs it straight into an MPEG encoder though. Right. I wouldn't be surprised if that encoder is a single chip designed to ingest TMDS so the 10-40Gb/s of raw data only travels a few mm. And MPEG encoding is the only reasonable way to handle data of this size, considering that it compresses 10Gbps down to <80Mbps and typically <10Mbps. > I believe any FPGA with a decent PCIe implementation should be able to bus-master, and if you set up the drivers properly you don't have to do anything with the kernel, it'll just allocate a block of transfer RAM for you. As for the first part, cool. With the 2nd part, you're seeing my complete lack of hardware knowledge :) I was envisaging having the host system "ignore" several GB of RAM - have linux's memory manager simply not touch it - and then turning it into a gigabyte+-wide circular buffer to copy into. Then, the processing/do-whatever code is written as a kernel module that "chases" after wherever the "head" is in the circular buffer (presumably this would be a pointer written to a fixed memory location). Because the buffer is gigabytes wide the kernel driver can stall (for whatever reason) for multiples of seconds and have wild swings in "chase performance" before there are any real issues. This design enables an important goal which I wanted to implement: pressing PrtScr or hitting a hardware button flushes the last few seconds of whatever was on the screen to disk - ie, you can achieve hardware-level, pixel-perfect, video capture. Frame glitch? Saved. "LOOK, the GPU displayed a single frame wrong again, agh, you missed it"? Saved. Weird timing glitch in graphics stack you can't reproduce? Saved. Weird timing/race-condition-related graphics issues that only happen when your test code is removed and are too fast to diagnose? Saved. Suddenly you can just spray debug data into the corner of the screen and analyze the captures later. Ideally, some simple compare-while-copying code running in the FPGA could store simple frame deltas and distil whole-screen updates into a list of changed rects. Maybe you could even do that on-CPU, as a kernel task. But here's the thing. In the worst case, with no compression/reduction code present, you'd be able to store 1 minute of 60fps 1080p in 20.85GB of RAM, and 6 minutes in 125.15GB. 1 minute of 3840x2160 uses 83.42GB, 3 minutes uses 250.28GB. 1 minute of 8K takes 333GB :D Of course, flushing to disk is a major operation; it would likely require multiple PCI NVMe devices, in either RAID or driven via a threaded storage engine, to flush the memory to storage fast enough - in the 8K example, you need to copy 333GB of RAM to disk in 1 minute, so your solution needs to receive 5GB (44.4Gb) per second, sustained, no performance spikes/dips. :P (This is where the gigantic circular buffer comes in to play; the idea is that the wraparound hits RAM with new data just as the old data got saved.) What's potentially interesting with this are the situations doing desktop-type work, small-scale tests, etc, where not all of the screen is going to be updated, and the reduction system will diff the updates very effectively. In these situations, if you're careful, you may go from minutes to tens-of-minutes or even hours of recording time, on a 128GB or 256GB RAM system. And that's only spending a few hundred $. (For the RAM, that is.) If you're doing game development - every screen effectively new data - and you need pixel-perfect HDMI capture, well, 2TB RAM workstations are only low/mid-5 figures now... > You can use multiple PCIe lanes easily? If you need more than an x16 slot I'd be very surprised. The GP mentioned that HDMI 2.1 is 42.7Gbps. Elsewhere in this thread it's mentioned that PCI-e's limit is 50Gbps. [EDIT: Just noticed the other comment about PCI-e speed. This makes things a little easier!]