Re: Keys get stuck

Helge Hafting
2008-03-13T14:25:08Z

Carlos R. Mafra wrote:
> On Thu 13.Mar'08 at 12:28:13 +0100, Mike Galbraith wrote:
>
>> [...]
>> Swap can definitely keep X off the cpu for extended periods,
>> [...]
>>
>
> So I would like to ask if swap letting X (and everything else
> in my experience) out of the cpu for extended periods is
> considered normal behaviour, in the sense that nobody is
> trying to "fix" it (due to it being considered impossible
> to fix)...?
>
Yes, this is perfectly normal. A heavily swapping machine
will swap out parts of X.

Now, if X has a need for low-latency for keyboard handling,
then the X developers can use mlock to lock
the X keyboard service in memory, and make it a real-time
(or at least high priority) process too. This should
avoid the problem even with extreme swapping and/or
high cpu load.

> Sorry for being off-topic, but I run a minimal Window Maker
> desktop in a P4 3.0 GHz with 512 MB of RAM (around 140 MB
> being used as per 'free'), and trying to load a 380 MB text
> file in xjed editor makes my whole desktop quite unfair...
> it takes tens of seconds to switch desktop, type things in
> the terminal etc.
>
>
Seems ou use too much memory then. If xjed
wastes memory (by bringing the entire file into memory
in one go) then you'll get some swapping.

> When xjed finishes loading the text file, everything comes
> back to "fair" again.
>
> Is there some law in the nature of computers which says
> that when swapping everything else waits for swap to finish
> its business? I hope not :-)
>
No such law, but there are badly implemented software
around. If xjed is capable of delaying all X events while
loading the file, for example . . .

Helge Hafting