Speed up DeviceKit device probing on really slow devices
torvalds at linux-foundation.org
Wed Jan 20 11:58:33 PST 2010
On Wed, 20 Jan 2010, David Zeuthen wrote:
> Well, the school of thought here is to collect as a lot of data (but not
> all - there's a fine line) about the device and store it in the udev
That's fine - but please keep in mind to collect it _after_ you have
exposed the device and made it useful. Because if it holds up actual real
work, it's a bad thing, not a feature.
Also keep in mind that some devices are rather unhappy with access
patterns that don't look like Windows. They've been tested with Windows,
and that's it. The kernel tries to fix them up, but there's a real risk
that being clever can make cheap USB sticks unusable.
Or not so cheap things, for that matter. Some iPod's are an example of
"crap that locks up if you try to read at the end of the device", where
the RAID probing literally killed the device (until the kernel got taught
to limit the size below what the device actually claimed).
So there are real downsides.
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