Re: [patch?] Re: Do ramdisk exec's map direct to buffer cache?

From: Linus Torvalds (torvalds@transmeta.com)
Date: Tue Aug 01 2000 - 16:51:39 EST


On Tue, 1 Aug 2000, Rik van Riel wrote:
>
> But with this "fix" you'd be adding another one in the
> process.
>
> Admitted, it's only a performance bug, but I found it to
> grind the machine to an absolute halt when doing IO
> intensive stuff or running large programs...

Performance bugs are definitely secondary.

> Stephen Tweedie, Andrea Arcangeli and me have been looking
> at this bug and others and have found there's pretty much
> NO WAY to fix this without some bigger changes in the VM
> code.

Quite frankly, nobody has convinced me that there any way to fix VM
balancing issues even _if_ people were to re-write the VM.

Yes, I've seen a lot of hot air.

The fact is that I suspect that it is fundamentally impossible to balance
the VM so that everybody is always happy. People should realize that
making more changes in the hope of finally reaching some elusive goal is
not always worthwhile.

Strive for a good, stable system that avoids _most_ of the bad performance
under normal load. And be prepared to live with the fact that there will
always be things you can do to make it behave in nasty ways.

Right now I want things to _work_. Big VM changes are for 2.5.x anyway.

(See 2.2.x for how playing with the VM can cause untold stability woes. I
think Alan learned that the hard way).

                Linus

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