Re: ~500 megs cached yet 2.6.5 goes into swap hell

Timothy Miller
2004-04-29T22:13:43Z

Paul Jackson wrote:
> Timothy wrote:
>
>>Perhaps nice level could influence how much a process is allowed to
>>affect page cache.
>
>
> I'm from the school that says 'nice' applies to scheduling priority,
> not memory usage.
>
> I'd expect a different knob, a per-task inherited value as is 'nice',
> to control memory usage.
>

Linux kernel developers seem to be of the mind that you cannot trust
what applications tell you about themselves, so it's better to use
heuristics to GUESS how to schedule something, rather than to add YET
ANOTHER property to it.

Nick, Con, Ingo, and others have done an impressive job of taking the
guess/heuristic approach to scheduling. I don't see why that can't be
taken further.

Also, there seems to be strong resistance to adding a property to
something which is not easily accessible through existing UNIX tools.
"nice" and "renice" commands have been around forever. Adding another
control requires new commands, new libc functions, changes to "top", etc.

Besides, when would you want to have a sched-nice of -20 and an io-nice
of 20, or a sched-nice of 20 and an io-nice of -20? Things like that
would make no sense.