Re: How do I make this thing stop laging? Reboot? Sounds like Windows!

From: Yaroslav Rastrigin (yarick@relex.ru)
Date: Wed Jun 18 2003 - 04:30:48 EST


Hi !
>
> Because the problem _is_ unsolvable. You want the kernel
> to go "oh, lots of free memory showed up, lets pull
> everything in from swap just in case someone might need it."
> ...
>
> It is simply impossible to know "what" the
> next thing we will need from swap will be, and what
> stuff won't ever be needed from swap. The memory
> might be putr to better uses, such as:
> 1. New programs/allocations can start without
> having to push something out first
> 2. file cache for io-intensive apps.
> ...
> Note that reading from swap is very much like reading
> from executable files - it is done when needed.
> We donŠ't normally pre-read every executable
> on the system when there is free memory just
> in case someone might want to run a program,
> the same applies to swap.
Well, the problem is probably unsolvable on kernel level (kernel is unaware of
user's habits in app/mem usage), but I think it's pretty solvable on user
level - give us a knob to tune VM's behavior. We mere mortals often know
better how we will use our system's memory, and which apps we will be
running. I, for myself, like laptop-mode patch (basically, it groups disk
writes to do them once in 5-10 minutes, thus allowing hdd to sleep a lot)
very much - when I'm on AC, most probably I'm in office , and turning it off
is reasonable. When I'm on battery, though, chances are I won't be compiling
the kernel and/or do other heavy disk IO, instead, I most likely will be
coding, so echo 1 >/proc/sys/vm/laptop_mode seems appropriate, reasonable and
useful.
Could something like this be done with VM/swap policy ?

-- 
With all the best, yarick at relex dot ru.

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