Re: [RFC] Heads up on sys_fallocate()

[David Chinner]

On Tue, Mar 06, 2007 at 10:46:56AM -0600, Eric Sandeen wrote:
> Ulrich Drepper wrote:
> > Christoph Hellwig wrote:
> >> fallocate with the whence argument and flags is already quite complicated,
> >> I'd rather have another call for placement decisions, that would
> >> be called on an fd to do placement decissions for any further allocations
> >> (prealloc, write, etc)
> > 
> > Yes, posix_fallocate shouldn't be made more complicated.  But I don't
> > understand why requesting linear layout of the blocks should be an
> > option.  It's always an advantage if the blocks requested this way are
> > linear on disk.  So, the kernel should always do its best to make this
> > happen, without needing an additional option.
> > 
> 
> Agreed on both points.  The hints would be for things like start block,
> or speculative EOF preallocation, not contiguity, which I think should
> always be the goal.

ISTR having had this discussion before ;)

About guided preallocation for defrag:

http://marc.info/?t=116247859500001&r=1&w=2

e.g.: The sorts of policies we need for effective use of
preallocation:

http://marc.info/?l=linux-fsdevel&m=116184475308164&w=2
http://marc.info/?l=linux-fsdevel&m=116278169519095&w=2

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group
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