Re: [PATCH 00/14] Pramfs: Persistent and protected ram filesystem

Marco
2009-06-15T17:47:03Z

Bryan Henderson wrote:
>> Marco wrote:
>>> To enable direct
>>> I/O at all times for all regular files requires either that
>>> applications be modified to include the O_DIRECT flag on all file
>>> opens, or that a new filesystem be used that always performs direct
>>> I/O by default."
>> This could be done as well by just introducing a "direct_io_only"
>> mount option to a file-system which would need this feature.
>
> But it's possible that there's just no advantage to having a block device
> in the stack here. When unix block devices were invented, their main
> purpose was that they could reorder reads and writes and do buffering and
> caching -- all things essential for disk drives. We don't want to stretch
> the concept too far.
>

Yes I agree, we can't in this case talk about read and write reordering,
buffering and caching because we're talking about something completely
different from a classic disk. The issues of this kind of fs are more
similar to the tmpfs issues.

Marco