Rockbox

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  • Task Type Patches
  • Category Drivers
  • Assigned To No-one
  • Operating System All players
  • Severity Low
  • Priority Very Low
  • Reported Version Daily build (which?)
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Attached to Project: Rockbox
Opened by pamaury - 2010-02-09
Last edited by pamaury - 2010-02-14

FS#10991 - Rewrite dircache generation to free ram and stack

This patch is a complete rewrite of dircache generation using some subtle properties of the FAT code. It currently doesn't contain code for the simulator ! It allows to free 30kib of ram and have a 600 bytes binsize reduction.

If you can test it, I'm particulary interested in:
* correctness: do you notice any problem ?
* stack usage: report dircache thread usage if you can

TODO: the current code doesn't add the "." and ".." entries in dircache for now. I don't know if it can cause problems.

   dircache-opt.diff (12.4 KiB)
Closed by  pamaury
2010-02-14 23:06
Reason for closing:  Accepted
Additional comments about closing:   Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407

r24657

pamaury commented on 2010-02-09 23:12

New version adding the "." and "..". I've noticed that putting the fat_ structures on the stack at the beginning leads to a big stack usage in the dircache thread. This could lead to a stokv on a very deep directory structure and I'm not sure at which depth.

The binsize reduction is of 200bytes with this version.

   dircache-opt-2.diff (12.9 KiB)
jdgordon commented on 2010-02-10 05:34

I've put this on my mini2g and I'll let you know any wierdness that shows up

jdgordon commented on 2010-02-10 21:31

no issus so far. Is there anything which especially shold be tested? Also it doesnt build for the sim.

pamaury commented on 2010-02-10 22:50

It's normal that it doesn't build for the sim (I've not written the code !). You can check not so usual operations such as rename, delete, … But if everything seems to work, then there shouldn't be any bug because it's really on the generation which changed.

pondlife commented on 2010-02-11 07:34

I've not been able to test this yet as I currenlty only have a sim, no device - but I'd hope that the sim shouldn't need any special code/#ifdefs at the dircache level. Ideally, any differences should be abstracted at the file system (FAT) level….

pamaury commented on 2010-02-11 16:20

I disagree, the simulator doesn't use the FAT code in any way (for now) so it makes sense to use a specialized version for the simulator in dircache.
This makes sense because the version I propose bypass the "normal" I/O api to use the FAT code which is an optimization only valid on a real target.
I'll try to upload an up to date version for the simulator quickly.

pamaury commented on 2010-02-11 17:57

New version:
-minor code change in dircache generation
-now there is code for the simulator

   dircache-opt-3.diff (15.5 KiB)
DrMoos commented on 2010-02-14 15:08

Tested on Gigabeat S:
All is working well here, no noticeable changes.

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