[RTEMS Project] #4635: untar on JFFS slow down

[RTEMS trac]

#4635: untar on JFFS slow down
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  Reporter:  Chris Johns  |      Owner:  (none)
      Type:  defect       |     Status:  new
  Priority:  normal       |  Milestone:  6.1
 Component:  fs/jaffs2    |    Version:  6
  Severity:  normal       |   Keywords:
Blocked By:               |   Blocking:
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 Using `untar` on JFFS is slower on rtems 6 compared to 4.11. The
 application writes files to the flash disk from an in memory tarfile and
 the difference is easy to see for 10M or so of files.

 I reviewed the changes to JFFS in rtems 6 and they look OK so it is not a
 regression the `libfs`. I also timed the flash driver and it is the same
 on 6 as 4.11.

 I noticed on 6 there is a lot more blocks being written at the flash
 driver level compared to 4.11. Looking at `untar` I see the block size
 written is `512` bytes and with compression this results in a lot of small
 blocks. Changing the `untar` block write size to 8K speeds returns the
 performance.

 I am not sure why there are more blocks on 6. A guess is the compression
 is better, which is is nice. I will not look into this any more than
 changing `untar` to use 8K blocks.

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Ticket URL: <http://devel.rtems.org/ticket/4635>
RTEMS Project <http://www.rtems.org/>
RTEMS Project