usb-storage filesystem corruption under FC2, kernel ...-435

[T. 'Nifty New Hat' Mitchell]

On Mon, Jun 14, 2004 at 06:28:22PM -0600, Fernando Perez wrote:
> 
> just reporting that even under today's kernel, the usb-storage problems are 
> still present (at least under some configurations).  I've been having this 
> problem ever since installing FC2.
....
> Jun 14 15:44:02 planck kernel: updfstab: Using deprecated /dev/sg mechanism 
> instead of SG_IO on the actual device

Two quick questions.
  * Why are you using a deprecated mechanism?
  * What type of file system is used on the USB device?

With hyperthreading on, you need symmetric multiprocessing support in
the kernel.  Just guessing, deprecated mechanisms are less likely to be
multi processor safe than the primary recommended mechanism.

The jury is still out on Linux and hyperthreading in my opinion.  Some
reports are less than an 15% advantage for common benchmarks.  You
might find that turning off hyperthreading gives you stability at a
cost you cannot measure in terms of performance at this time.

While I am an AMD fan, hyperthreading is cool hardware.  Should Intel
add a couple extra logic blocks so threads are a bit more equal then
some interesting OS things might happen.  Right now there is less
symmetry than I 'think' is needed.  I also suspect that cache memory
is the key limiting resource for ia32 linux and that additional
virtual processors/threads do not expose enough power to justify the
additional OS overhead.

Regardless there is a bug and it is not likely to be fixed on a
deprecated functionality.  Pursue it main line if you can.  I suspect,
like you, that it is related to hyperthreading.  If you cannot suffer
the errors or time to debug ... turn off hyperthreading(SMP) as the
most likely problem and when you see reports that it is fixed turn it
back on and test.


-- 
	T o m  M i t c h e l l 
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