Inplace upgrade from 5.4 to 5.6.1

      We are upgrading from 5.4 to 5.6.1 . We have  lots of content (assets, pages etc) in 5.4 and now we want to do inplace upgrade to 5.6.1.Did this inplace upgrade re-index all the assets again ? Any rough estimate how much time it takes for 100 gigs data  We have done a garbage collection before upgrade too

Thanks

Karthik