Re: Patch for **MAJOR** HFS.FST Bug

[bazyar@hypermall.com (Jawaid Bazyar)]

Soenke Behrens (sbehrens@contech.demon.co.uk) wrote:
: now that HFS is stable, I'm wondering about its other short-coming: It
: is excruciantingly slow. According to Joachim Lange (of BlueDisk
: fame), one of the main reasons for this is that the HFS FST writes
: blocks _backwards_ on a Multi-Block Write Request.

: That, obviously, means you lose a lot of speed: After each written
: block, you have to wait a revolution before the next one comes around.
: There goes all your clever interleaving.

: It sure would be interesting to know the rationale behind this: Is it
: an oversight? Was Apple doing this deliberately? If so, why? Does the
: HFS FST _really_ work that way?

: I can't for the life of me think for a good reason to code it thusly.
: Being able to have a DEC/BNE loop is not a good reason :). Am I
: overlooking something vitally important here?

  If that's indeed the way it operates, it would account for part of
the poor performance. Not being able to read a chunk of a disk at once
would have dire performance consequences, especially on hard drive.

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