Sorry, I misunderstood your question. There probably will not be a lot
of 512-byte block I/O -- not in the workloads I'm acquainted with. But
there will be some.
It isn't performance-critical, in the sense that slowing down the odd
512-byte block transfers won't hurt performance much. But it is
critical in the sense that the transfers must work properly when they
do occur.
You mean, have the USB stack allocate bounce buffers and copy the data
between the S-G buffers (which may be in high memory) and the bounce
buffers? We're talking about a potentially fairly large amount of
data, say up to 100 KB. Is that really easier than splitting up an I/O
request?
Alan Stern
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