> Re: [2.4.17/18pre] VM and swap - it's really unusable
>
>
> My observation:
> Why does the kernel swap to get free memory for caching / buffering? I
> can't see any sense in this action. Wouldn't it be better to shrink the
> cashing / buffering-RAM to the amount of memory, which is obviously free?
>
> Swapping should be principally used, if the RAM ends for real memory
> (memory, which is used for running applications). First of all, the
> memory-usage of cache and buffers should be reduced before starting to
> swap IMHO.
>
My main "problem" with 2.4 as well. Using free memory for Cache/Buffers
is great, but only as long as the memory is not needed for running
tasks. As soon as a task is requesting more memory, it should be first
taken from Cache/Buffer (they are caches, aren't they :-). Only if this
has been used up (to a tunable minimum, see below), swapping and finally
OOM killing should happen.
To prevent completely trashing IO performance, there should be tunable
parameters for minimum and maximum Cache/Buffer usage (lets say in
percent of total memory). Maybe those tunables are even there today and
I am just to stupid to find them :-))
In any case, 2.4 Caches/Buffers show to much persistance. This is
basically true for both branches of VM. I was using the -ac kernels
because, being far from perfect, the VM gave considreabele better
interactive behaviour.
> Or would it be possible, to implement more than one swapping strategy,
> which could be configured during make menuconfig? This would give the
> user the chance to find the best swapping strategy for his purpose.
>
That is another option. But I would prefer something that could be
selected dynamically or at boot time.
Martin
-- +-----------------------------------------------------+ |Martin Knoblauch | |-----------------------------------------------------| |http://www.knobisoft.de/cats | |-----------------------------------------------------| |e-mail: knobi@knobisoft.de | +-----------------------------------------------------+ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Mon Dec 31 2001 - 21:00:22 EST