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Intel Developers Demo USB 3.0 Throughput On Linux

Posted by timothy on from the future-sweetness dept.

Sarah Sharp writes "Intel's Open Source Technology Center is working on USB 3.0 support for Linux. USB 3.0 has wire speeds of 5Gbps and promises to be 10 times faster than USB 2.0. A recent video demo shows speeds that are 3.5 times faster than USB 2.0. The USB 3.0 drivers will be submitted to the mainline kernel when the eXtensible host controller interface (xHCI) specification reaches a 1.0 release."

62 of 231 comments (clear)

  1. What's in a name... by alain94040 · · Score: 5, Insightful

    USB 2.0 gave us high-speed and full-speed. Some marketing department had to work really hard on the USB 3.0 specs, to come up with... super-speed.

    Now let's talk about the obvious problem: at 5 Gbit/s, it's faster than the Ethernet in my house (1 Gbit/s). Am I the only one who didn't really notice a 10X speed improvement when moving from 100 Mbit Ethernet to gigabit Ethernet? Conventional hard drives are just too slow.

    Maybe SSD + USB 3.0 would be really cool. Imagine a Flash based HD camera talking to a Flash based hard drive. Is 2009 the year of the Flash?

    Which brings me back to my original point: for the next generation USB, I propose the name flash-speed :-)

    PS: thanks to Intel for helping Linux stay on the leading edge. It looks like Linux may even support this before Windows, thanks to the Windows 7 schedule... I just wish Intel's pre-conditions on contributing to the xHCI specs didn't start with stuff like:

    Step 1. Print and execute the xHCI Contributor agreement. Note: The agreement must be executed by a corporate officer.

    --
    http://fairsoftware.net/

    1. Re:What's in a name... by Swizec · · Score: 2, Interesting

      What I'm wondering with the SSD computer + USB3 + Flash camera combo is ... does the computer even have enough processing power to complete the transaction while letting the user multitask somewhat normally?

      Or would the whole thing somehow circumvent the need to tell the OS what's going on with the file system?

    2. Re:What's in a name... by Anonymous Coward · · Score: 2, Funny

      Look, we both know that there will be a "USB ludicrous speed". Marketing has no say in it.

    3. Re:What's in a name... by Microlith · · Score: 3, Informative

      Imagine a Flash based HD camera talking to a Flash based hard drive.

      Maybe if said HD camera has a USB host controller, like that USB-2-GO stuff.

      Otherwise, I suspect USB 3.0 is as braindead as USB 1.0 and will still require a computer to do all the actual work.

    4. Re:What's in a name... by Mad+Merlin · · Score: 2, Interesting

      The thing is that USB is bursty, in practice you'll probably still get much better speed out of Gigabit ethernet than you will with USB 3.0.

      As for Gigabit ethernet, it's a massive upgrade from 100 megabit ethernet, at least in my usage. It only takes 2 modern drives in RAID 0 to saturate Gigabit ethernet, or just 1 fast SSD.

      --
      Game! - Where the stick is mightier than the sword!
    5. Re:What's in a name... by Microlith · · Score: 4, Insightful

      This is why Intel is pushing USB: it is entirely CPU dependent.

      You won't notice it when you're running with X * 2 logical cores. It'll be shuffled off to some low utilization core.

    6. Re:What's in a name... by John+Allsup · · Score: 5, Interesting

      I guess for hard drives, the question is how close to eSATA it gets.
      Also, does USB3 still have the CPU overhead and latency of earlier USB compared to FW?

      --
      John_Chalisque
    7. Re:What's in a name... by Mad+Merlin · · Score: 4, Informative

      'bursty' ... is that sort of like 'minty'? ;)

      No, it's that max speeds for USB 2.0 refer to the max burst speeds, not the maximum sustainable speed. A single 7200 RPM drive attached via USB 2.0 will be substantially slower than if you attached it via SATA or IDE, even though 60 MB/s (= 480 Mbit/s) should be enough for most drives.

      --
      Game! - Where the stick is mightier than the sword!
    8. Re:What's in a name... by commodoresloat · · Score: 2, Funny

      Is 2009 the year of the Flash?

      Indeed. On the desktop!!

    9. Re:What's in a name... by metalhed77 · · Score: 4, Interesting

      That USED to be true. It's not the hard drive, all the layers that get put in between when you access a disk over the network. Modern hard drives can easily do 60MB/s sustained.

      For instance, I have a couple raid6 arrays which clock in at about 250 MB/s and 150MB/s natively. If I hook that machine up directly to another machine's ethernet port I only get about 30MB/s sharing the device w/ iSCSI. SMB and NFS yield similar results. This is true even though I can get over 900Mbps using iperf.

      Sharing disks over gig-e sucks when you actually need throughput. It's great for when you just need to expand a SAN and speed is secondary. I've heard that bonding two Gig-e cards doesn't realize much of an improvement FWIW, so I assume latency is part of the reason it's slower.

      --
      Photos.
    10. Re:What's in a name... by gad_zuki! · · Score: 2, Informative

      >Am I the only one who didn't really notice a 10X speed improvement when moving from 100 Mbit Ethernet to gigabit Ethernet?

      Well, youre probably not getting 10x. Depending on a slew of factors (your switch, cable length, etc) youre getting anywhere between 100 to 800 mbps. Have you tried any speed tests? With gigabit I can copy to my nas at 25 megabytes per second. At 100 I was getting under 12. So that's twice the speed for me, which is most likely limited by the CPU on my nas and not ethernet.

      >Conventional hard drives are just too slow.

      Not really. Current drives go way past the limitations of USB2. We need a faster USB. Firewire is dying so USB needs to take up the slack on fast local connections. Shame esata isnt taking off with the home market.

      >It looks like Linux may even support this before Windows, thanks to the Windows 7 schedule

      USB 3.0 will work like any device: with a driver. I expect both XP and Vista to have it as manufacturers will simply write their own drivers without waiting for MS to package it into a service pack.

    11. Re:What's in a name... by Hal_Porter · · Score: 2, Interesting

      Honestly, Intel didn't have much choice, the NT kernel can't exactly be obtained, modified and distributed for free

      At the moment Windows supports three host controller drivers. OHCI and UHCI for USB 1.0 and EHCI for USB 2.0. There's nothing special about host controller drivers, anyone can write one. If they wanted they could write a host controller driver for xHCI and then Windows would support USB 3.0.

      --
      echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
    12. Re:What's in a name... by LoRdTAW · · Score: 2, Informative

      Gigabit Ethernet is a vast improvement over 100Mbit. Two windows boxes with fast SATA drives I see no less than 20 megabytes/second transfer speeds on a Vista64 XP64. Top speeds exceed 30 MB/sec (~300+Mbps)! My home server runs Linux but for some reason SAMBA is dog slow no matter how much I tweak the damn conf file. 10-12MB/sec tops for Linux Windows (without tweaks it was 3-4MB/sec!).

      I have a four disk 1.5TB raid 5 array using SATA disks on a pciX controller and mdadm. Copying from the array to an **old crusty 20 gig ATA** root drive I see 40+ MB/second! So saying today's drives are too slow is not the case. I would love to see the speed with an SSD, bet it would easily soar over 100MB/sec! Wish SAMBA could keep up.

      I have yet to actually test my Linux notebook with NFS to the server as I just use wireless so its always going to be slow. But saying you see no increase means you aren't really taxing the network.

      PS if anyone knows how to speed up SAMBA under Ubuntu 8.04 please let me know. I used all the tcp_nodelay and the other tcp settings but nothing really works.

    13. Re:What's in a name... by Anonymous Coward · · Score: 2, Funny

      We've gone plaid.

    14. Re:What's in a name... by mog007 · · Score: 2, Funny

      What about ludicrous speed?

      --
      Learn something new.
    15. Re:What's in a name... by Gazzonyx · · Score: 4, Funny

      USB 2.0 gave us high-speed and full-speed. Some marketing department had to work really hard on the USB 3.0 specs, to come up with... super-speed.

      I'm holding out for WARP speed...

      I'm holding out for plaid speed...

      --

      If I mod you up, it doesn't necessarily mean I agree with what you've said, sorry.

    16. Re:What's in a name... by averagegeek · · Score: 2, Funny

      PS: thanks to Intel for helping Linux stay on the leading edge. It looks like Linux may even support this before Windows, thanks to the Windows 7 schedule

      The real question is...will Tux get fat with all the new code?

    17. Re:What's in a name... by More_Cowbell · · Score: 3, Interesting

      I appreciate the answer, but you replied to the bit where I was trying (poorly) for humor. I know what burst speed vs sustainable speed is all about. What I wanted you to explain is what makes you think a medium that has a burst speed of 4.8 Gbit/s will not be able to sustain > 1 Gbit/s (like your ethernet). I have read a bit, and not seen any info either way...

      --
      Experience teaches only the teachable. -AH
    18. Re:What's in a name... by billcopc · · Score: 2, Informative

      Yes, but the difference is a USB device or controller costs about 2 yen, while a Firewire endpoint costs about $20, half of that in licensing alone!

      Firewire is by far a superior interlink in terms of performance, but it is overpriced (you can thank Steve Jobs for that one).

      --
      -Billco, Fnarg.com
    19. Re:What's in a name... by 0100010001010011 · · Score: 3, Informative

      The agreement essentially brings patents held by these companies into a single portfolio that can then be licensed by manufacturers for a single fee. That fee is US$.25 per system that includes FireWire ports, regardless of the number of patents used or the number of FireWire ports implemented. This is a dramatic decrease from the US$1 per port per device (see "Apple To Charge 'Per-Port' Licensing On FireWire") that Apple originally announced it would charge for its own patents.

      $10 is not in licensing fees.

    20. Re:What's in a name... by Mr+Z · · Score: 3, Informative

      Protocol latency is a big deal. If you have a large per-transaction overhead, then the overall throughput of a given medium will be very sensitive to the number of transactions it creates on the media, as opposed to the total number of bytes it needs to move.

      That's part of the reason the HTTP sprouted request pipelining, since the round-trip-time between the endpoints of the connection figured largely in the startup latency of each connection.

      It sounds like the typical PC implementation of USB relies heavily on the CPU to handle all but the lowest levels of the protocol. (I'm relying on hearsay here.) If this is indeed the case, then it'll be hard for USB to reach the max sustained speeds for storage devices, unless there's a mechanism for requesting large blocks of data (or large numbers of small blocks) in a single transaction.

      For us old-school types, it's similar to the reason XMODEM didn't get much faster with faster modems over a certain speed. XMODEM didn't pipeline anything. It'd send a block, and then wait for an ACK. Since the latency of fancier modems was higher than the simple FSK 300 baud modems, the handshake turnaround time of the ACK swamped the gains made while sending the blocks. (Also, the tiny block size didn't help.) Thus, pipelined protocols like ZMODEM and large-block non-pipelined protocols (XMODEM-1K) came about to address this.

      --
      Program Intellivision!
    21. Re:What's in a name... by 0100010001010011 · · Score: 4, Informative

      Again, bull shiat. Use google before stating "recent developments."

      USB 2.0 was released in April 2000.

      Those licensing fees were announced in May 1999.

      In Jan 1999 Apple announced that it would be $1 per port. As far as I know it's always been $1 per port. Now I don't know of any devices with 10 ports on them (Making the licensing fee $10). Here's a CNET article from the same time.

      Both were before USB2.0 was released and considerably less than what you claim.

    22. Re:What's in a name... by saharabeara · · Score: 3, Informative

      Hmm, a crappy host based implementation at 5Gbps or a storage targeted, low everhead one at 3Gbps (possibly going to 6Gbps if the next gen spec gets extended to eSATA), I know which one I will use =)

      Actually, USB 3.0 was targeted for mass storage devices. They added the concept of Bulk Streams to support "out-of-order data transfers required for mass storage device command queuing." (USB 3.0 spec, section 4.4.6.4) Basically, the host can queue up to 65K SCSI commands, and the device can choose which command it wants to service first.

      The host doesn't have to poll the device to see when commands are done because they added device notifications to USB 3.0. So the host fires off 65K of SCSI requests and the device asynchronously notifies the host as they get done. I'm no firewire expert, so I have no idea if it does something comparable. :)

  2. Re:3.5x faster by imamac · · Score: 2, Informative

    Uh. No. In 1996 FireWire was at 393 Mbit/sec (S400 standard). USB 3 seems like it will be plenty faster. There is more than jus speed advantage, though. FireWire likes to change plugs at every new generation. USB does not.

  3. Re:3.5x faster by Anonymous Coward · · Score: 2, Insightful

    If we're talking actual real world speeds (not the theoretical best case scenario ideal lab conditions crap), then yeah, that's about where FireWire sat in it's first iteration.

  4. Wha? by Weaselmancer · · Score: 4, Informative

    Could you please explain that a bit?

    It's my understanding that high throughput drivers usually use DMA.

    In my experience polled mode drivers are pretty rare. Especially in high throughput.

    --
    Weaselmancer
    rediculous.
    1. Re:Wha? by Lost+Engineer · · Score: 3, Insightful

      USB 2.0 requires the host to control all communication on the bus, and in practice uses more CPU time than something like 1394. I don't know if they changed this in USB3 or not.

    2. Re:Wha? by Anonymous Coward · · Score: 2, Informative

      The fact that USB is a polling protocol is a very low level decision. The CPU does not need to regularly ask each device for data. The USB controller does that.

    3. Re:Wha? by Hal_Porter · · Score: 5, Informative

      Yup the host sets up a structure in memory which lists all the USB endpoints. When a driver wants to do some IO it asks the host controller driver which adds a request into the structure with a pointer to a buffer. The host controller hardware reads the structure with busmaster DMA and generates the USB packets. When the device answers the host controller DMAs the data into the the driver's buffer interrupts the CPU. Then the host controller can pass the buffer back to the driver. Polling is done by leaving the request in the structure, it doesn't require any CPU activity. Intel like USB because they invented it, not as some sort of conspiracy to load your CPU.

      --
      echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
    4. Re:Wha? by lysergic.acid · · Score: 4, Interesting

      so why do FireWire 400 readers still consistently beat out USB 2:

      While USB 2.0's theoretical 480Mbp/s (60MBp/s) throughput should be sufficient for UDMA 4 CompactFlash, realthroughput is significantly less. Top hard drive manufacturers typically cite USB 2.0's best speed at 33MB/s, or abouthalf the speed of UDMA 4 CompactFlash, or 25% of UDMA 6 CompactFlash. There are myriad reasons for USB 2.0's'real world' speeds including: CPU overhead from its master/slave arrangement, NRZI encoding, and inexpensivechipset implementations. The USB 2.0 UDMA reader used in the benchmarks above uses one of the latest USBchipsets from Genesys Logic. While a new generation of that chipset should soon be available, we don't foresee itproviding throughput close to half of that of FireWire.

      heck, those benchmarks show that even using FireWire 400 to read a PIO CompactFlash card still beats USB 2.0 UDMA reading a UDMA-enabled CompactFlash card.

    5. Re:Wha? by raynet · · Score: 5, Informative

      Taken from wikipedia: "Although high-speed USB 2.0 nominally runs at a higher signaling rate (480 Mbit/s) than FireWire 400, typical USB PC-hosts rarely exceed sustained transfers of 280 Mbit/s, with 240 Mbit/s being more typical. This is likely due to USB's reliance on the host-processor to manage low-level USB protocol, whereas FireWire delegates the same tasks to the interface hardware. For example, the FireWire host interface supports memory-mapped devices, which allows high-level protocols to run without loading the host CPU with interrupts and buffer-copy operations."

      --
      - Raynet --> .
    6. Re:Wha? by yoyhed · · Score: 4, Insightful

      Yup the host sets up a structure in memory which lists all the USB endpoints. When a driver wants to do some IO it asks the host controller driver which adds a request into the structure with a pointer to a buffer. The host controller hardware reads the structure with busmaster DMA and generates the USB packets. When the device answers the host controller DMAs the data into the the driver's buffer interrupts the CPU. Then the host controller can pass the buffer back to the driver. Polling is done by leaving the request in the structure, it doesn't require any CPU activity. Intel like USB because they invented it, not as some sort of conspiracy to load your CPU.

      I know it's off-topic, but I thought I'd point out why I love Slashdot by comparing it to Digg. If this story were on Digg, the comments would be something like "I BET THIS BE ON NEXT MACBOOK PRO LOL". Here, we get something like your comment in the first thread. <3 /.

      --
      WHO NEEDS SHIFT WHEN YOU HAVE CAPSLOCK/ DAMN1
    7. Re:Wha? by mabhatter654 · · Score: 4, Informative

      This is why you can't have USB-to-USB devices like you have Firewire-to-Firewire devices. It's why USB is very bad for time-sensitive data like music and video, because you're always waiting for the host controller to do something on the CPU, which might be busy.. have you ever seen DMA to memory ever work properly on consumer grade hardware anyway?

      It's not so much a "scam" as it is designing to the market. Firewire devices have a non-trivial price premium because of the device-to-device controller... but that's why they can do things like daisy-chain or direct connect between computers with no special cables. On the other hand USB allows endpoint devices to be made very cheaply.. they have near-zero intelligence if you want. The USB host can be as "thick" or "thin" as the OEM wants... they can put all the host chip control in software drivers to keep chip cost down. They can also put all the control codes for devices in software... remember "wINKjets" that went obsolete with each new Windows version... they have almost no internal software at all.

    8. Re:Wha? by lysergic.acid · · Score: 4, Interesting

      good point. and to be honest, most people don't need FireWire 800/1600 just to transfer a few documents or spreadsheets--or even photos & mp3s--to their computer. the few seconds saved doesn't justify the added cost of FireWire over USB. nor do they need to use a high-speed data bus for their mouse, keyboard, webcam, printer, scanner, or what have you. so it makes sense that USB is more prevalent than FireWire.

      however, FireWire is still extremely useful (and crucial) to certain professionals who regularly work with large files or have to move around large amounts of data, like hi-res/raw images, lossless audio, hi-def video, etc. that's why FireWire is still pretty standard in high-end music & video production equipment. so the idea that FireWire is dead (or can simply be replaced with USB 2.0/3.0) is just poorly informed.

      even the military still uses FireWire for things like the the F-35's vehicle systems network:

      1394b is playing a pivotal role in the F-35 Lightning II program, providing guaranteed quality of service with predictable latencies in real-time control applications. More than 70 1394 devices are delivering information about mission details, communication systems, weapon systems, engine controls, and flight controls.

      the IEEE-1394B data bus is similarly employed in the F-22 Raptor for which it was developed. and NASA also uses it to monitor debris during launches amongst other mission-critical applications.

    9. Re:Wha? by afidel · · Score: 3, Informative

      have you ever seen DMA to memory ever work properly on consumer grade hardware anyway?
      Yeah, every day. PIO mode HDD's suck terribly, DMA is necessary to achieve decent performance.

      --
      There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
    10. Re:Wha? by dgatwood · · Score: 2, Insightful

      What I don't get is why anybody cares about USB 3.0. For disks, its performance will suck compared with eSATA for lots of reasons (lack of true DMA, slower bus, more protocol overhead etc.). For any serious audio/video tasks, FireWire works a lot better and is already generally fast enough for 99.9% of users (and PCIe is a great alternative for that .1%). For all other devices, USB 2.0 is fast enough (and for that matter, USB 1.1 was usually fast enough). What's the intended market for this technology? It seems like it is designed to be fast just to be fast, with no real thought given to why they're making USB faster.

      IMHO, USB 3.0 might have made some sense before eSATA's introduction. Now, it really doesn't, particularly given that it can't be made board-layout-compatible with existing USB 2.0 silicon because of the need to wire up the extra optical components for the 3.0 hardware. If you have to do a new board layout for 3.0 anyway, you might as well just switch to the far superior eSATA standard....

      --

      Check out my sci-fi/humor trilogy at PatriotsBooks.

    11. Re:Wha? by eh2o · · Score: 2, Informative

      That isn't correct--USB also has an isochronous transport mode that guarantees timely access and bandwidth to a streaming device.

      Also there is USB On-The-Go (OTG) which is for ad-hoc point-to-point communication between devices without a host controller. That was released as a 2.0 spec supplemental and is commonly found in ... printers that you can plug your camera into, for example.

  5. Motherboards by Enderandrew · · Score: 2, Interesting

    When can I buy my first motherboard that is USB 3.0 compliant? I want to build a rig in the spring. I'd consider holding off until the summer to get USB 3 so it is more future proof, but I won't wait another year.

    --
    http://blindscribblings.com - Tasty pop-culture in conceptual fashion.
    1. Re:Motherboards by kklein · · Score: 3, Insightful

      Please don't say "rig."

  6. Re:cool, at least it is progress by thermian · · Score: 5, Funny

    yeah yeah, i read the comments about gigabit ethernet being faster, thats not the point, usb 3 is still better than usb 2, enjoy the weekend...

    We're geeks, reading stuff like this *is* enjoying the weekend.....

    --
    A learning experience is one of those things that say, 'You know that thing you just did? Don't do that.' - D. Adams
  7. latency badness by r00t · · Score: 4, Interesting

    USB suffers from 1 ms time quantization and thus latency. I see nothing about fixing this.

    Example badness:

    When running MIDI over USB, timing is forced onto 1 ms slots. Normally when playing a chord, the keys don't all hit at exactly the same moment. You can't really tell, except that this makes the music sound natural. With the 1 ms problem, the keys happen at exactly the same moment (bad) or spread out into two separate events (worse).

    1. Re:latency badness by setagllib · · Score: 2, Informative

      Sampling and encoding the events before they hit the limited USB connection is. That requires extra equipment, however.

      --
      Sam ty sig.
    2. Re:latency badness by saharabeara · · Score: 2, Informative

      USB suffers from 1 ms time quantization and thus latency. I see nothing about fixing this.

      Example badness:

      When running MIDI over USB, timing is forced onto 1 ms slots. Normally when playing a chord, the keys don't all hit at exactly the same moment. You can't really tell, except that this makes the music sound natural. With the 1 ms problem, the keys happen at exactly the same moment (bad) or spread out into two separate events (worse).

      Yes, USB 3.0 is still quantized. However, USB 2.0 devices can be sampled more often than 1ms. The 1ms frame was broken into 8 microframes in USB 2.0. I'm not a sound engineer, but it seems like you could have some buffering on the device side to send several sound samples with time stamps in one microframe. The software on the other side could re-space out the samples. Would you really notice a 125 us delay when playing music?

    3. Re:latency badness by PiSkyHi · · Score: 3, Funny

      ...yes and 2 completely separate transfer cables, 1 for all the ones, the other for all the zeros.

      Gold plated, of course.

  8. Compared to USB 1... by MonoSynth · · Score: 5, Interesting

    This shows where Linux is nowadays. It took literally years before USB1 was even supported and now Intel uses Linux to prove USB3's performance!

    1. Re:Compared to USB 1... by MSG · · Score: 4, Informative

      Too bad they used Windows to show it performing about twice as fast as the Linux test ...

      The tests were nothing alike. The Linux demo was sending data to an actual storage device, not to a loopback device designed only to test throughput. The Linux driver also had a great deal of debugging code running which contributed to the relatively low throughput.

      None of which is to say that Linux was or deserved to be the star of this show. It's nice, however, to see technology vendors demonstrating software on platforms other than Windows.

  9. Future Problems..... by IHC+Navistar · · Score: 2, Funny

    USB 1.1: Low-Speed and Full-Speed

    USB 2.0: High-Speed

    USB 3.0: Super-Speed

    USB 4.0: Mega-Speed

    USB 5.0: Ultra-Speed

    USB 6.0: ???-Speed

    --
    Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
    1. Re:Future Problems..... by Jeoh · · Score: 4, Funny

      USB 7.0 Monster-Speed USB 8.0 Ludicrous-Speed USB 9.0 HOLY SHIT

    2. Re:Future Problems..... by Briareos · · Score: 3, Funny

      USB 7.0: Profit-Speed!

      --

      "I'm not anti-anything, I'm anti-everything, it fits better." - Sole

  10. Firewire Not Dead, Doing Pretty Good Actually by Anonymous Coward · · Score: 3, Interesting

    Whenever a story about USB3 is written, the following caveats should be mandated by law if necessary:

    1. Speed claims are theoretical, and do not reflect real-world results by a long shot. Lots of overhead, CPU dependence, etc.

    USB2 promised 480Mbps and never delivered it. You get 250Mbps on a good day. Now we have marketing claims that USB3 will be "10x faster," yet a video demo shows it's 3.5x faster. That's 1.5Gbps, not 5Gbps.

    2. Firewire 3200 is approved and on the way. It will be faster than USB3, backward-compatible with FW800 (same cables and ports) and should begin appearing on Macs in January. Firewire isn't dead; Firewire 400 is being eased out in favour of faster versions.

    If FW 3200 performs like its predecessors, it should be (in real-world usage) routinely about 2x faster than USB3.

    Moral of the story: don't settle for mediocre.

  11. There's throughput and then there's latency by Gazzonyx · · Score: 3, Interesting

    Well, I get high throughput with my NIC drivers that poll (I can't remember the kernel compile option for this ATM), but this is at the cost of a higher latency. The trade off is that I've got 5 NICs on this box and it turns out that without polling I get close to having an interrupt storm and spend all my time switching context to execute the drivers bottom half of the interrupt. With polling, the interrupt gets masked and I don't have to worry about servicing every interrupt coming down the line. My latency is higher, but I get more throughput for every time I service the bus as it has more packets to process. This also means I'm trading off space for time (I need larger ring buffers to queue packets) such that I have less memory for the system, but processes get more time on the processor between interrupts.

    While not having to do with USB, the driver architect and concepts are likely very much the same.

    --

    If I mod you up, it doesn't necessarily mean I agree with what you've said, sorry.

    1. Re:There's throughput and then there's latency by LarsG · · Score: 2, Interesting

      I seem to recall that some Linux drivers try to handle this automatically (Intel gigabit chips?). They do interrupts when the traffic is below some threshold and switch to polling when things get busy. The main reason, as you say, is to avoid interrupt storms; polling becomes cheaper on CPU time than interrupts when there is a higher than x% chance of there being packets waiting. It is also more resilient to DoS or server overload - if f.ex. an Apache server receives more requests than it can handle, throttling the polling speed makes more CPU available for handling requests instead of wasting it in interrupts receiving packets that the web server is too overloaded to handle anyway.

      --
      If J.K.R wrote Windows: Puteulanus fenestra mortalis!
  12. Security by MSG · · Score: 2, Informative

    An awful lot of people are looking down their noses at USB 3 because it's not Firewire. Has everyone forgotten that Firewire grants devices DMA access to physical memory? Any physically connected device can be used to bypass the system's security. I'm grateful that USB isn't more like Firewire.

  13. Comment removed by account_deleted · · Score: 4, Interesting

    Comment removed based on user account deletion

  14. Re:cool, at least it is progress by TheRaven64 · · Score: 3, Insightful

    So is FireWire400, once you subtract the protocol overhead from both. Will USB 3 be faster than FireWire800 (which I have been using for the last few years) in real world use? And will FireWire3200 be shipping by the time USB3 is found in real products?

    --
    I am TheRaven on Soylent News
  15. The real big thing... by wikinerd · · Score: 3, Informative

    Wake me up when Firewire over UTP gets popular. THAT would be interesting.

  16. Who needs USB anymore ? by billcopc · · Score: 4, Interesting

    Why are they wasting everyone's time with USB 3.0, when the rest of the universe is shifting toward Ethernet as a common interconnect ? Note I didn't say IP, just Ethernet - good old CAT-5.

    Frig, if the audio folks have already started that transition, then what the hell is Intel doing ? The audio industry is probably the most retarded in the world (according to my failed expectations), and even they see that Ethernet is a cost-effective and braindead simple replacement for all these proprietary cables we've had to contend with over the years.

    --
    -Billco, Fnarg.com
    1. Re:Who needs USB anymore ? by afidel · · Score: 3, Informative

      If that's a troll it's a good one, but you can provide 7.5x more power over ethernet then the USB spec allows (15.4W vs 2.5W). 802.3at pushes things even further to 24W max.

      --
      There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
    2. Re:Who needs USB anymore ? by Save_Clippy · · Score: 2, Funny

      Wake me up when we've got Power over WIRELESS Ethernet. Thanks.

  17. Speed isn't everything by mmcuh · · Score: 2, Interesting

    One thing that is at least as important for free software systems as speed increases is class compliance. Take audio and MIDI devices for example. Almost all USB 1.0 audio and MIDI devices are class compliant, and thus work reasonably well with the standard kernel module snd-usb-audio. But with USB 2.0 that changed for some reason - now many more devices require special drivers that often do not exist for Linux. It would be nice if Intel and friends could somehow push for more class compliant USB devices.

    1. Re:Speed isn't everything by eh2o · · Score: 2, Informative

      USB hasn't changed the approach towards class compliance, and they continue to improve those related specifications. If you want to point fingers, look at the hardware and software vendors. FTDI, for example, makes a nearly ubiquitous USB-serial chip that is not class compliance in spite of the fact that every major OS supports the serial device class.

  18. What's in a name...Corporate GTA. by Ostracus · · Score: 2, Funny

    "Step 1. Print and execute the xHCI Contributor agreement. Note: The agreement must be executed by a corporate officer."

    Those corporate officers have all the fun, executing this, executing that.

    --
    Shai Schticks:"You don't make peace with friends, you make peace with enemies"