David Lively
2007-Nov-12 18:37 UTC
[Xen-devel] [PATCH] make dirty logging stop requiring physical pages of order > 0
Per Keir''s suggestion from a couple weeks ago, this patch re-implements the (x86) hypervisor dirty page log with a simple four-level radix tree whose nodes are all single pages, thus making migration require only order-0 pages (where before it required at least an order-5 page). Unlike the p2m radix tree implementation, the interior nodes of this tree are NOT page table nodes. I chose a lazy-allocation and -mapping approach because most pages are not marked dirty while dirty-logging is enabled. There are doubtless situations (the ''stream'' benchmark, for example) where a more complex p2m-like approach is faster, but I''m not sure they''re worth the effort. This is a port of my 3.1.2 patch, which has tested well for a week+ now (w/64 bit hypervisor and HVM guests only). For various reasons, it hasn''t yet been tested on unstable, but there were very few modifications necessary to make it run there. (I''m not going to get it tested before the Xen summit, so I thought it would be best to go ahead and post it ...) Signed-off-by: Dave Lively <dlively@virtualiron.com> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel