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SubjectRe: support for sata7 Streaming Feature Set?
Jeff Garzik wrote:
> Tejun Heo wrote:
>> One thing to think about before supporting streaming from/to harddisks
>> from userland is how to make data flow efficiently from userland to
>> kernel and back. But, no matter what, kernel <-> userland usually
>> involves one data copy, so I don't think making sg similarly efficient
>> would be too difficult (it might be already).
>
> Actually, the kernel usually maps userland pages, eliminating the need
> for a copy. write(2) may have copied data into that page originally,
> but mmap(2) need not have.

Yeap, to achieve high streaming rate, it would be best to have
preallocated ring buffer and ring pointers. If this high-bw streaming
thing becomes common, we can add it to sg, I guess.

--
tejun
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