Posted May 12, 2011 18:46 UTC (Thu) by dlang (✭ supporter ✭, #313)
In reply to: Stable pages by jzbiciak
Parent article: Stable pages
the COW can be further optimized by not turning on COW until the system is ready to start processing the page
if you have a page that's being modified 1000 times a second, you don't want to have 1000 copies/sec to try and write out.
but while the system is working to write the first copy, you can allow the second copy to be modified many different times, and only when you select that page for writeout (and are ready to do the checksum on it), do you set COW.
this will get the modifications to disk as quickly as the disk will support it, but will only have one copy of the page (in addition to what's in the process of being written out to disk)