

Windows 8: Building robust USB 3.0 support - justanotheratom
http://blogs.msdn.com/b/b8/archive/2011/08/22/building-robust-usb-3-0-support.aspx

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kazuya
This article is not actually about USB. Neither about Windows 8.

What's interesting is that Microsoft uses model checking on real shipping
products. In fact it has been pushing static checker (SLAM and SDV) for years.

Other operating systems including Linux have their own verification projects,
but they all appear to stay academic (though look promising).

We can expect more reliable operating systems in this decade. Maybe.

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justincormack
Actually looking foward to USB 3, not the speed but the fact there is command
queuing for usb storage, which makes ssd performant (without queuing you get
far fewer iops, factor of about 10 from memory)

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justanotheratom
Can you elaborate on what command queuing is, and whether it helps sequential
or parallel transfers?

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megrimlock
Command queueing allows the device controller to handle requests out of order.
Since it has intimate knowledge of the hardware it can order requests for
maximum throughput.

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justincormack
Actually a USB bus doesnt know much about the hardware, but can forward
multiple simultaneous (SCSI) requests and if the hardware is fast it can deal
with them in whatever order it wants.

If you benchmark an SSD with and without queueing you get very different
speeds; with hard drives there is still a difference, although not as much.

EDIT benchmarks (Intel SSD)

no queuing, 4k reads: 3965 iops depth 4 , 4k reads: 16,900 iops depth 8, 4k
reads: 25,700 iops depth 16, 4k reads: 32,600 iops depth 32, 4k reads: 38,800
iops

The benefit decreases with larger reads, but still exists.

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kenjackson
USB 3.0 is cool and all, but I'm not sure I'd start the Win8 engineering
discussion there. With that said, it's probably a cool feature that doesn't
require showing off any new UI.

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paulo_gws
Meanwhile Apple is building robust Thunderbolt support.

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watmough
This is starting to look like a move to have engineers promoting various
aspects of Windows 8. Great stuff, and I hope it keeps up.

These two videos make me feel like I want a copy of Windows around again. In
particular, the showing multiple apps on screen, the way that was done just
seems right, and pretty much the way I hoped the iPad would work, but sadly
no.

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drv
I found the part about designing the system with flowcharts in Visio and
generating code based on the flowcharts, and apparently the model is validated
based on the flowcharts as well.

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bdonlan
What did you find it?

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fungi
Linux started supporting USB 3.0 in the September 2009 release of the 2.6.31
Linux kernel.

[http://kernelnewbies.org/Linux_2_6_31#head-2c74ce6091fb2feb4...](http://kernelnewbies.org/Linux_2_6_31#head-2c74ce6091fb2feb4f1dec5973c72f68879c8c86)

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runjake
And this matters in this context why?

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sliverstorm
Your parent probably glossed over "robust" and imagined that Windows 7 must
not actually support USB 3.0 yet.

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starwed
Actually, after reading the entire article that is _exactly_ the impression it
gives.

-edit- A quick google also leaves the impression that Windows support for USB 3 is new.

<http://www.google.com/search?q=windows+usb+3+support>

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sliverstorm
It's certainly not native in Windows 7, but I don't see how you get the
impression it is not supported at all.

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starwed
Isn't native support the issue at hand?

