Re: Kernel device driver programming

On Sat, 19 Feb 2005, Arthur Corliss wrote:

> Character devices are typically used for unbuffered non-random access. Block
> devices are mandatory random-access, and are a bit more complicated to
> initialise (requiring a strategy routine, etc.). The reason why you see so
> many tutorials on character devices is because they're much simpler to deal
> with in general.

I should have also pointed out that with block devices you operate almost
exclusively on the buffer cache. If you're writing to a hardware device (like
a disk controller) this can help you maximise throughput via the strategy
routine, by reordering writes into a more efficient pattern, etc.

Ultimately, which is faster is going to depend on what you're actually writing
to.

        --Arthur Corliss
          Bolverk's Lair -- http://arthur.corlissfamily.org/
          Digital Mages -- http://www.digitalmages.com/
          "Live Free or Die, the Only Way to Live" -- NH State Motto
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Received on Sat Feb 19 11:34:21 2005