tech-kern archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: write alignment matters?

>> [...disk buffer alignment issues...]
> I suspect most disk controllers will have issues if the buffer is not
> aligned on at [least] 16bits.

Perhaps.  In such cases, something else in the I/O stack - the device
driver, most likely, since this is a device-hardware issue - has to
compensate.  Paying an extra copy penalty for a misaligned buffer may
be annoying, but it's better than getting I/O errors or other weird
violation of the interface's semantics.

The issue for me is not that the hardware does or doesn't have
alignment restrictions.  It's that they show through to userland (and
in a very peculiar way).  As someone mentioned upthread, it's possible
what's going on is that this hardware has alignment issues (at least
when used with our sequencer program) the driver _doesn't_ deal with.

/~\ The ASCII                             Mouse
\ / Ribbon Campaign
 X  Against HTML      
/ \ Email!           7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B

Home | Main Index | Thread Index | Old Index