vykon jadra

Robert Vojta vojta na ipex.cz
Čtvrtek Červen 7 10:21:46 CEST 2001


> sel po reinstalaci z jadra 2.2.16 na 2.4.2 nejmene o 100% dolu. Pomuze mi to
> rozresit rekompilace jadra, nebo mam pridat pamet (mam ji 56 MB (64MB - 8MB
> ukusuje onboard grafika)). Dekuji za jakekoliv nakopnuti.

  Co ta masina presne dela? Viz lkml a prave probihajici a docela dost se
zvetsujici thread "Break 2.4 VM in five easy steps" ...

...
>After reading the messages to this list for the last couple of weeks and
>playing around on my machine, I'm convinced that the VM system in 2.4 is
>still severely broken.

Now, this may well be true, but what you actually demonstrated is that
"swapoff()" is extremely (and I mean _EXTREMELY_) inefficient, to the
point that it can certainly be called broken.

It got worse in 2.4.x not so much due to any generic VM worseness, as
due to the fact that the much more persistent swap cache behaviour in
2.4.x just exposes the fundamental inefficiencies of "swapoff()" more
clearly.  I don't think the swapoff() algorithm itself has changed, it's
just that the algorithm was always exponential, I think (and because of
the persistent swap cache, the "n" in the algorithm became much bigger). 

So this is really a separate problem from the general VM balancing
issues. Go and look at the "try_to_unuse()" logic, and wince.
...

Best,
  .R.V.

-- 
   _
  |-|  __      Robert Vojta <vojta-at-ipex.cz>          -= Oo.oO =-
  |=| [Ll]     IPEX, s.r.o.
  "^" ====`o
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