Performance optimization in av::fixup - use buffered IO, not mapped file

Daniel Colascione
Thu Dec 13 19:03:00 GMT 2012

On 12/13/12 2:39 AM, Corinna Vinschen wrote:
> On Dec 13 01:44, Daniel Colascione wrote:
>> What about using the automatic sparse handling in lseek/lwrite and
>> ftruncate only when the file being operated on is already sparse?
> That doesn't make sense.  If the file is already sparse, there's no
> reason to set the sparse flag in write or ftruncate again.  Also, if you
> set the sparse flag only on already sparse files, you will never be able
> to create sparse 

Yes, you're right. I thought I remembered a separate call we could
have retained to actually punch a hole in a sparse file. I checked
the code, and all we do is set the sparse flag.

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