[ltp] Re: Interference of wlan usage and hdaps?

[Henrique de Moraes Holschuh]

On Wed, 23 Sep 2009, Elias Oltmanns wrote:
> Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> Excessive spinning in sw interrupt context has a rather severe impact on
> other timers running at the time. If they have fired shortly after the
> atheros tasklet has started, the interrupt handler is delayed
> considerably. Apart from everything else, this really messes up hdapsd's
> book keeping, thus making it believe that a minor change in the accel
> data has occurred in a particularly short time frame. For all hdapsd
> knows, this indicates an emergency condition and it parks the heads
> accordingly.

That just means hdapsd has a severe design issue.  It should use timestamped
events, and it should look at the timestamps to get the time component,
instead of assuming it is being fed an isosynchronous stream...   It should
also do something sensible if it notices it is processing old data :p

AFAIK the input layer does timestamp events at the time they are issued by
the kernel.  If it doesn't, we need to move to something that does :-)

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh