Thread: just saw the n9 and i really want too sell n900
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shadowjk is offline shadowjk
2010-09-09 , 22:35
Posts: 1,258 | Thanked: 672 times | Joined on Mar 2009
#52
Originally Posted by wmarone View Post
It doesn't have a hard disk. The only thing that could possibly be fragmented is the swap partition, and being solid state memory fragmentation would have zero impact.
Well for reads the impact of seeking isn't that big (mostly command overhead I think). For writing the impact is gigantic though. The native erase block size is something like 128-256k, while the OS and MMU deal in units of 4k. When the OS issues a 4K write, the emmc will read 256k, modify 4k of that, and write it back. Slowdown is factor 64 or so, not counting command overhead from issuing many small requests instead of fewer big ones.

Of course swap fragmentation disappears with a reboot or swapoff/swapon cycle.