On Sat, Apr 28, 2018 at 11:55 AM, Jan Hubicka <hubi...@ucw.cz> wrote: > Hi, > with number of cores increasing our partitioning algorithm needs some love, > because it works quite bad. > > This patch fixes few issues with ballanced partitioning algorithm: > 1) I have switched all size/boundary summaries to 64bit arthmetics as they > may overflow for very large units > 2) internal calls within partition was misaccounted > 3) I no longer account external references (as those will never be local > no matter how we partition) > 4) the range where we search for best split is not +- 1/8 of partition. > 5) we no longer look for worst possible split, but for best one. > 6) I have added bit extra debug info. > > I have checked this with Firefox build. Previously we did 31 instead of 32 > partitions > and the difference between largest and smallest was 170%. Now we do 32 > partitions and get > the difference is "only" about 70%. The resulting code quality improves a > bit and > we get 260s for largest partition build time instead of 305s. > > I will commit it into the mainline and backport to release branches after > some soaking > (and 8.1 release), since without the patch partitioning decisions with larger > # of partitions > are really pretty bad. > > Situation is still not perfect - I do not get any speedup for increasing > partitions to 64 > becuase we still get too much of extra streaming. Something to track this > stage1. > > Honza > > * lto-partition.c: Include sreal.h > (add_symbol_to_partition_1): Use size instead of self_size > for size estimate. > (account_reference_p): New. > (lto_balanced_map): Use 64bit arithmetics for size calculatoins; > cleanup; > fix accounting errors in boundary size; add debug output; combine cost > as cost/size instead of cost/internal; reduce the partitioning error > to > +- 1/8 of the parttion size.
This caused: FAIL: gcc.dg/lto/20081204-2 c_lto_20081204-2_0.o-c_lto_20081204-2_0.o link, -w -flto -fPIC -r -nostdlib (internal compiler error) FAIL: gcc.dg/lto/20090914-2 c_lto_20090914-2_0.o-c_lto_20090914-2_0.o link, -O2 -flto -fuse-linker-plugin (internal compiler error) FAIL: gcc.dg/lto/20091014-1 c_lto_20091014-1_0.o-c_lto_20091014-1_0.o link, -fPIC -r -nostdlib -flto (internal compiler error) FAIL: gcc.dg/lto/20100603-1 c_lto_20100603-1_0.o-c_lto_20100603-1_0.o link, -O0 -flto -fuse-linker-plugin -fno-fat-lto-objects (internal compiler error) FAIL: gcc.dg/lto/20100603-1 c_lto_20100603-1_0.o-c_lto_20100603-1_0.o link, -O2 -flto -fuse-linker-plugin (internal compiler error) FAIL: g++.dg/lto/20081120-1 cp_lto_20081120-1_0.o-cp_lto_20081120-1_1.o link, -flto -r -nostdlib (internal compiler error) FAIL: g++.dg/lto/20081120-2 cp_lto_20081120-2_0.o-cp_lto_20081120-2_1.o link, -flto -r -nostdlib (internal compiler error) on x86. -- H.J.
