ASU - out of memory?

[Carsten Haitzler (The Rasterman)]

On Thu, 21 Aug 2008 12:58:44 +0200 Tilman Baumann <tilman at baumann.name> babbled:

> Carsten Haitzler (The Rasterman) wrote:
> > On Thu, 21 Aug 2008 11:42:52 +0200 Tilman Baumann <tilman at baumann.name>
> > babbled:
> > 
> > no.. you need to find who is leaking memory and beat them up! :) seriously.
> > 128m is more than enough. it's almost overkill. needing swap (on a device
> > like the freerunner) is a sign of "stupid programming" :)
> 
> I understand your Argument and it is true. But the conclusion is wrong.
> Even if you don't have obvious leaks, some memory will not be used most 
> of the time and can be safely dumped out of the RAM.
> Like some background process which is sleeping almost all the time. Or 
> other multitasked apps which are not used currently.
> Or all the fat frameworks which probably take some memory for code or 
> data which are almost never used.

given the abysmal IO speed flah and sdio can manage - not to mention the
overhead and waitstates we get from swapping via glamo... i'd sooner want to
tear out my eyeballs than have anything swap over SD...

> All this memory is wasted on valuable RAM. Even if only a hand full of 
> pages end on swap, they are saved from clogging up RAM.
> 
> And using huge amounts of virtual memory is not necessarily a effect of 
> a memory leak. Virtual memory is almost free after all on all other 
> linux systems.
> 
> And another point is just the more graceful effect when memory really 
> becomes low.
> You feel the speed impact. You feel that something needs to be done. Or 
>   some popup can ask the user for some intervention - all before it is 
> too late.
> 
> As i said, swap on flash sound crazy. But i had this experience on my 
> Nokia 770 (64Mb RAM). Even if i was not always on the memory limit, it 
> felt instantaneously better and more stable.

i think its just the lazy mans way out. "there's a problem" .. "look - lets
cover it up by swapping!". 128m ram is a huge amount. most of the time a vast
chunk of it (at least 25%) be "cache" - i.e. memory you dont need - but it just
kept around in case you need it again soon. the only thing we are talking here
is using swap in favor of using that space for disk cache really. given we have
things like sd card corruption problems on suspend/resume... not to mention
performance issues, i'd think it would make little sense so make the system
that fragile. fix the memory usage issue - don't just "get more slow slow slow"
ram. :)

-- 
Carsten Haitzler (The Rasterman) <raster at openmoko.org>