On Sun, Oct 24 2010 at 9:03pm -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > dm-kcopyd: Delayed unplug of the queues > > This patch improves performance aby about 20% when writing to the snapshot > origin. We keep track of two block devices to unplug (one for read and the > other for write) and unplug them when exiting "do_work" thread. If there are > more devices used (in theory it could happen, in practice it is rare), we > unplug immediatelly. Again, more specifics on how you realized this 20% performance would be appreciated. I'd imagine this patch is really where the increased latency comes back (due to removing immediate unplug)? But does the fact that >2 devices will unplug immediately mitigate the worst of the higher latency (e.g. for DM mirrors with >2 legs)? Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
