Messages in this thread |  | | | Date | Thu, 18 May 2006 11:36:50 -0400 | | From | Jeff Garzik <> | | Subject | Re: support for sata7 Streaming Feature Set? |
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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.
Jeff
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