On 05/23/2007 09:28 PM, Ingo Molnar wrote:
* Rene Herman <[email protected]> wrote:
The trouble there is that unless you poll the bloody thing like mad
too much of the Q subchannels passes below you and you need a huge
number of retries to get anything out of it. I noticed when I started
adding audio bits that the driver took full seconds to complete some
audio requests while the old driver was snappy in that regard. When I
replaced our sleeping loop with a busy-wait same as the original the
snappyness returned and moreover, reading the TOC from the CD went
from something close to a minute to approximately a second. Thought
that minute was just because I was dealing with an old junk 1-speed
drive...
ouch ...
Indeed...
then i guess the right approach is to not use jiffies but to use a
calculated number of udelay(10) calls or so.
I'm not sure that will do -- the disc is still spinning below us while we're
delaying/sleeping. Alan just now suggested checking need_resched which
sounds like okay advice. I'll be trying what still works...
(given that noone uses these drives for anything serious anymore I'm in fact
also not overly worried about being a busy-looping pig and just saying "this
hardware sucks, why are you using it?").
Rene.
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