Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: fix CONFIG_HIGHPTE | Date | Fri, 9 Aug 2002 16:07:24 +0200 |
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On Wednesday 07 August 2002 04:57, Andrew Morton wrote: > Anton Blanchard wrote: > > On ppc64 shared pagetables will require significant changes to the way > > we handle the hardware hashtable. So add that to the "more and more crap > > in there to support these pte_chains" > > Last I heard, pagetable sharing wasn't working out too well > because they all get unshared.
That's only when you fork from a process with a minimal amount of VM mapped, such as bash, which has 3 page tables allocated to it, all of which get unshared. The situation is entirely different if you fork from a process that has malloced more than a few meg, or beaten on a large mmap. Page table sharing turns in a significant win there.
> > Will shared pagetables be a requirement or can we turn it on per arch? > > It's doubtful if per-arch would be an option.
It's currently expressed as a config option. As it's purely an optimization there's no reason to do otherwise. Disabling it per-arch should be trivial.
> - We'll continue to suck for the University workload.
That seems likely ;-)
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