Why not copy around data in physical RAM?

Posted Sep 9, 2004 10:56 UTC (Thu) by rwmj (subscriber, #5474)
In reply to: Why not copy around data in physical RAM? by scarabaeus
Parent article: Kswapd and high-order allocations

I actually suggested this on kernel-list many years ago. Alan Cox's (correct) objection was that it would require scanning lists to find out where a page was used. As you point out, rmap means you don't need to do that scanning any more.

So the idea would be, if higher-order allocations are not available, pick the largest available allocation, then start evicting physical pages used above this allocation.

The only case when this wouldn't work is when trying to do an atomic allocation - but it's very hard to satisfy large, atomic allocations anyway.

Rich.