Niall’s virtual diary archives – Monday 15th April 2013

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Monday 15th April 2013: 6.36pm. Link shared: https://plus.google.com/109885711759115445224/posts/Ltn4JzAS9LX

Finally got my mSATA USB 3.0 enclosure which I had to order from the US. With a Crucial M4 mSATA SSD inserted, my Samsung ARM Chromebook gets:

iozone -e -I -a -s 1000M -r 4k -r 512k -i 0 -i 1 -i 2

                                                            random  random    bkwd   record   stride                                   
              KB  reclen   write rewrite    read    reread    read   write    read  rewrite     read   fwrite frewrite   fread  freread
         1024000       4   10509   11524    11235    11548    9039   11808                                                         
         1024000     512   38881   39764    40345    40290   39491   38930                                                          

In other words, about 10Mb/sec for 4k reads and writes with no real difference if they're random. And a peak transfer rate of ~38Mb/sec, also with no real difference if it's random. All these suggest it's the USB 3.0 controller which is getting in the way. These results were expected of course (see https://plus.google.com/109885711759115445224/posts/Ltn4JzAS9LX).

If there ever was an example of USB 3.0 controller limited performance, it is the above: Samsung's Exynos 5 ARM chipset's USB controller really is not great. That SSD should hit 250Mb/sec reads over USB 3.0 :(

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