杨苏立 Yang Su Li wrote: > Connecting an SSD to a cell phone is actually my initial idea. I > wanna try memory/ramdisk because I need fine control over the I/O > speed I get. As memory is a true random access device, Even DRAM isn't completely random access, but memory controllers do a good job at faking it. I agree that as far as a USB 2.0 bottleneck is concerned, DRAM can be considered random access. > I can get uniform access time, thus its performance is much easier > to understand/reason about. In the contrast, SSD/HDD is something > complicated with sophisticated caching/relocating going on. So it > is hard to predict how long your next I/O request is going to take..... Yep. > However, I realize there might not be such a thing which connect a > DRAM/SDRAM card to USB port. So I might have to settle for SSD, and > strive to find an SSD which offers the most predictable performance... If you can find one of the old PLX cards then that is worth a try. > I am quite concerned about the USB 2.0 speed indeed. Is there a way to > turn an USB 2.0 cellphone/tablet into an USB 3.0 host by, say, adding > some kind of hardware? Unfortunately not without designing a different computer using different components. > Without large enough DRAM (at least several GB) Beagle board is > definitely out. No way I could change its DRAM card to a larger one? Unfortunately no way. Instead of a card, the memory is a BGA package soldered on top of the CPU. Keyword: package-on-package > >> > design special purpose hardware > > OK. Then this solution is out too (at least for now). Yes, understandable. //Peter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
