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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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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