Re: [9fans] plan 9 overcommits memory?

[john@csplan9.rit.edu]

>> Also, it's broken, broken, broken on Plan 9
>
> but could you describe what antisocial behavior it exhibits and how one
> could reproduce this behavior?  i have never used to-disk paging on plan 9,
> so i don't know.
>

Well, when I used it on an old 32 MB laptop (terminal) and a 64 MB
desktop (cpu server), swap would seem to work all right until you
hit about 30-40% usage. This was the case with both systems; when
I asked about it, a couple other people mentioned the same behavior.
The thing is, it's pretty hard to test swap under normal usage; the only
time I ran into this problem was while compiling a new kernel.

>> and nobody wants to fix it.
>
> this has been a good discussion so far.  let's not go off in a bad direction.

I was just noting that when it has previously come up, the general
consensus is that nobody wants to fix it, which is actually pretty
reasonable--I'm guessing, as has been mentioned before, that the
number of people who could potentially need/want swap is very low,
especially since memory for older computers seems to grow on trees
(around here at least).

>
>> The upside to this is that we can just say how we don't want it anyway,
>> there's no conceivable reason anyone would want swap,  and operating
>> systems with working swap suck ;)
>
> not sure how to parse this.  is there a particular case where you need to-disk
> paging?  i don't see the use of to-disk paging.  perhaps my vision is limited.
>
> in the one case where i might find it useful  -- in embedded systems, there's
> typically more ram than persistant storage, so paging to "disk" makes no sense.
>

It's primarily old systems, I think, like that old laptop which wasn't worth
finding more RAM for. When I set up this shiny high-spec cpu server,
I let it put in swap space "just in case", but a couple users barely put
a dent in that, so it will probably never be used.