> > I plan to commit it shortly (i am just slowly progressing through the > > bugreports and TODOs cumulated) > > - indeed for bigger apps and edit/relink cycle it is an life saver ;) > > I haven't tested exactly around this, but I see a ~10s (~5%) improved kernel > LTO build time going from 4.9-20140209 to 20140220
Good to know! It also improves firefox build noticeably. I added some comments to the PR itself. I do not see how it can make too many WPA processes, given that it does not fork without explicit -flto=N argument that is not passed by the bootstrap-lto.mk config. So perhaps something is wrong with parsing command liine arguments and setting lto_parallelizm? Also for all builds I tested so far the memory is not dominated by WPA streaming but by the subsequent ltrans-es now. Things are different with -fprofile-generate that adds a lot of extra datastructures to stream. Generally I am trying to convince people to profile without LTO as it is much faster. I will try to reproduce the problem - but I am running ltobootstraps and profiled-ltobootstrap regularly and never saw too many WPA processes at once. Honza
