On Aug 5, 2019, at 11:25 AM, Stephen John Smoogen <[email protected]> wrote:
>
> On Mon, 5 Aug 2019 at 13:17, Jerry Geis <[email protected]> wrote:
>
>> Why is it that "all" I am really doing at the moment is copying things to
>> an external SSD disk USB3 connected and the machine "freezes"... Why is
>> that?
>>
> You may have a motherboard which is routing a lot through a single USB
> controller. When that happens your graphical workstation will slow down
> because your keyboard and mouse events and some other polling has to
> complete before it can do the next thing.
Ridiculous if true. Modern OSes solved the blocking I/O problem decades ago.
Consider: you may have a gigabit Ethernet connection to the Internet, and it is
probably throttled to a small fraction of that speed by your ISP, yet you can
be pumping hundreds of giga*bytes* per second to your SSD while your browser is
blocked waiting for the remote server to respond. Further, while one site is
being slow to respond, another background Internet task can use the idled
Internet connection.
This is a symptom of a real problem, and it may be well worth chasing it to the
ground.
Jerry: Try another I/O channel for the same copy. For example, what happens if
you rsync the same file set to a remote machine, with the USB SSD connected to
*that* machine? Or, if you have a Thunderbolt or FireWire option, try that
instead. It might even be worth dropping a PCIe card into the machine for an
alternative I/O path just to help diagnose this. If nothing else, it might
solve the problem.
USB is a terrible standard, emblematic of everything wrong with the PC world.
We were sold USB-C as the grand unification of Thunderbolt and classic USB, but
what we actually got are 6+ different and partially incompatible flavors of
USB-C!
https://people.kernel.org/bleung/how-many-kinds-of-usb-c-to-usb-c-cables-are-there
https://news.ycombinator.com/item?id=20444326
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