On Wed, Jan 09, 2013 at 12:44:38AM -0500, Mikulas Patocka wrote: > We maintain a history of kcopyd usage in variables io_period and > total_period. The actual kcopyd activity is "(100 * io_period / > total_period)" percent of time. If we exceed user-defined percentage > threshold, we sleep. Well, I'm going to take this pair of patches for now. Some people do need this throttling today and this seems to me to be a decent and simple way to give them a lever to deal with the problem. I'm not proposing we expose this through LVM or other userspace tools at this stage: people who need it should tune it directly through sysfs. If need be, we can revisit this in future either by refining the algorithm or making it adjustable per-device rather than per-module. (Or by re-vamping kcopyd itself...) The current version is: http://people.redhat.com/agk/patches/linux/editing/dm-kcopyd-introduce-configurable-throttling.patch Alasdair -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
