Re: objrmap-core-1 (rmap removal for file mappings to avoid 4:4 in <=16G machines)

Arjan van de Ven
2004-03-08T21:29:57Z

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> . Basically without
> this fix it's like 2.6 is running w/o pte-highmem. 700 tasks with 2.7G
> of shm mapped each would run the box out of zone-normal even with 4:4.
> With 3:1 100 tasks would be enough. Math is easy:
>
> 2.7*1024*1024*1024/4096*8*100/1024/1024/1024
> 2.7*1024*1024*1024/4096*8*700/1024/1024/1024

not saying your patch is not useful or anything,but there is a less
invasive shortcut possible. Oracle wants to mlock() its shared area, and
for mlock()'d pages we don't need a pte chain *at all*. So we could get
rid of a lot of this overhead that way.

Now your patch might well be useful for a lot of other reasons too, but
if this is the only one there are potential less invasive solutions for
2.6.

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