Re: [PATCH 0/4] Fix performance burning or extracting audio etc. from multiple optical drives.

[Tim Small <tim@seoss.co.uk>]

On 05/11/15 01:38, Wakko Warner wrote:
> I tested on a system with 3 drives.  ejecting all drives didn't happen at
> the same time, but I think it's because they are different brands and one
> didn't have a disc in.  I did notice the leds coming on about the same time
> though.  eject -t on all drives happened at the same time.
> 
> The patch I used previously on 3.3.0 removed all mutex_lock and mutex_unlock
> lines from sr.c where as this patchset didn't.  I plan on trying to burn 3
> dvds to see if it works.
> 
> Thanks for your work on the patches.

No problem.  I haven't had any time to follow up (and probably won't for
the foreseeable - I've got far too much on at the moment unfortunately),
and the locking issues looked non-trivial unfortunately.

In my testing burning, and audio extracting etc. worked pretty
flawlessly IIRC, it was just the eject/load path which seemed to have
locking issues.

The test was just a shell scripts which ran:

while true ; do eject /dev/sr0 ; eject -T /dev/sr0 ; done

for every drive in the system simultaneously.

Hopefully it's a good start if someone wants to pick it up.  It's
possible that there's an easy way of leaving the old mutexes (or adding
more) around the relevant open/eject/load paths only, but I can't
remember the code now unfortunately.

If anyone wants to have a go, I think I can probably rig up about 8
drives to a testrig here, and will be happy to give it a test.

Tim.