Re: Note describing poor dcache utilization under high memory pressure

From: Rick Stevens (rstevens@vitalstream.com)
Date: Mon Jan 28 2002 - 18:12:47 EST


Daniel Phillips wrote:

> Since the page was copied to the child, the child's page table must be
> altered, and since it is shared, it must first be instantiated by the child.
> So after all the dust settles, the parent and child have their own copies of
> a page table page, which differ only at a single location: the child's page
> table points at its freshly made CoW copy, and the parent's page table points
> at the original page.

>
> The beauty of this is, the page table could just as easily have been shared
> by a sibling of the child, not the parent at all, in the case that the parent
> had already instantiated its own copy of the page table page because of an
> earlier CoW.

Ok. Still seems like a bit more copying than necessary. I'd have
to look at it a bit more and do some noodling.

 
> Confused yet? Welcome to the club ;-)

Does my head exploding qualify for "confused"? If so, then I'm not
yet "confused". I'm "concerned", since my ears are bleeding (a
precursor to an explosion) ;-p

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- "More hay, Trigger?" "No thanks, Roy, I'm stuffed!" -
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