#10045 HIGH 1.5-sof: XO-1.5 Record audio/video are out of sync with each other

John Watlington wad at laptop.org
Tue May 11 19:10:01 EDT 2010

On May 11, 2010, at 3:55 PM, Mikus Grinbergs wrote:

>>> Does this get better with a Class 6 card?
>> Yes, you then get consistent high performance. No need to run any
>> tests, just use the system and note its smoothness.
> I've been running a class 6 card (by PQI) in my B2 XO-1.5 for about two
> weeks now.  While there is an improvement in responsiveness, I would not
> be willing to swear to an absence of "unexplained long delays".

Yes, class 6 cards are nicer.
The problem is that in the quest for the lowest cost laptop, the cost of the SD
card is an easy target.   Moving from class 6 to class 2 (or from 4GB to 2GB)
is one of the few ways to knock $3-4 off the price of the laptop, and has proven
irresistible to Quanta and the OLPC Association.

OLPC (Foundation) could put its foot down, and insist on Class 6 cards --- I've
qualified a number of Class 2 and Class 6 cards.    Or perhaps a better
solution would be to encourage deployments to test and decide for themselves.

Martin is right that my test scripts aren't checking for speed.   They collect
information on that, but are mainly looking for bit errors and the effectiveness
of wear levelling.

Remember, my priorities are:
1. Lower Power
2. Lower Cost
3. More Robust
4. More Performance

> ----
> Each time I install a new build, I apply the same customizations (using
> data already stored on my external_slot "permanent" SD card (class 6)).
> These involve installing some rpms, then doing some 'vi' and mainly
> some 'cp'.  At least twice during this customization process, some
> individual command takes much longer than normal to complete.  My own
> guess as to the probable cause was 'garbage collection' by python.
> IIRC, these "unexpected delays" have not vanished with the installation
> of the class 6 microSD card.
> Also (relevant to the topic of this thread), in Record on the XO-1.5
> there is a noticeable delay between when I wave my hand "on camera", and
> when that motion shows up on the screen.  My impression was that in
> switching the microSD card from class 2 to class 6 this "lag" got
> shorter - but it is definitely still there.
> mikus
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