The problem is that the writes are being done in 4096 blocks
(...)
Which tells me that perl it's self has set the 4096 from somewhere else

Not really sure, but maybe your problem has to do with PerlIO having a fixed buffer size of 4k (hardcoded in the Perl source).  See Re: 4k read buffer is too small.

In reply to Re: Fuse / Fuse::Simple write_buffer issues by almut
in thread Fuse / Fuse::Simple write_buffer issues by jamescondron

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