Re: 2.1.125 Show stopper list: Draft

Perry Harrington (pedward@sun4.apsoft.com)
Wed, 14 Oct 1998 11:52:04 -0700 (PDT)

> > NetBSD handles this very elegantly. Because the overhead of page
> > table recovery is pretty foul (especially non intel), when they need
> > to reclaim memory urgently they simply blow the CPU page tables away
> > and give the task a new empty page table set to page everything back
> > into.
> >
> > Since there are caches these faults don't go to disk but just to the cache
> > and rapidly recover the page tables for the current working set.
>
> But surely with enough small segments I could overflow these caches too?
> Doesn't sound like a complete solution to me.
>
> -Andi
>

This is reasonable, assuming that the caches are vmalloced. This means
the caches are pagable, not locked. You could certainly wreak havoc on
a non-x86 machine, but the fact is that you only blow the cache for the
process that's causing the problems. Therefore, the DoSing process will
suffer great performance penalties and only affect itself.

Not much of a problem as I see it.

--Perry

(BTW, Alan, read your /. post, I remember when those lcc vs bcc wars were :)

-- 
Perry Harrington       Linux rules all OSes.    APSoft      ()
email: perry@apsoft.com 			Think Blue. /\


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