Il 05/02/2014 10:09, Dr. David Alan Gilbert ha scritto:
I think the case Alexey is hitting is: 1 A few dirtied pages 2 but because of the hpratio most of the data is actually zero - indeed most of the target-page sized chunks are zero 3 Thus the data compresses very heavily 4 When the bandwidth/delay calculation happens it's spent a reasonable amount of time transferring a reasonable amount of pages but not actually many bytes on the wire, so the estimate of the available bandwidth available is lower than reality. 5 The max-downtime calculation is a comparison of pending-dirty uncompressed bytes with compressed bandwidth(5) is bound to fail if the compression ratio is particularly high, which because of the hpratio it is if we're just dirtying one word in an entire host page.
So far so good, but why isn't pending-dirty (aka migration_dirty_pages in the code) zero?
Paolo
