My validate has a few perf failures (below). Now I know that sampling heap size is inaccurate, but the evidence here is pretty strong. Also validate fell over completely in my 2GB VM when Haddock ran out of memory, I had to give it more memory to complete. Something has got worse recently - this wasn't happening a couple of weeks ago. Does anyone have any idea what might have caused this? Going back in time is difficult. Are these failures happening for other people? Let me suggest something that might help with these perf tests: running the program with +RTS -h -i0.01 will give a more accurate indication of peak residency, by running major GCs much more often. Also you get a heap profile. Cheers, Simon =====> haddock.base(normal) 2474 of 3806 [0, 1, 0] max_bytes_used value is too high: Expected max_bytes_used: 96022312 +/-10% Lower bound max_bytes_used: 86420080 Upper bound max_bytes_used: 105624544 Actual max_bytes_used: 113537216 peak_megabytes_allocated value is too high: Expected peak_megabytes_allocated: 274 +/-10% Lower bound peak_megabytes_allocated: 246 Upper bound peak_megabytes_allocated: 302 Actual peak_megabytes_allocated: 323 *** unexpected failure for haddock.base(normal) =====> haddock.Cabal(normal) 2475 of 3806 [0, 2, 0] =====> haddock.compiler(normal) 2476 of 3806 [0, 2, 0] peak_megabytes_allocated value is too high: Expected peak_megabytes_allocated: 1250 +/-10% Lower bound peak_megabytes_allocated: 1125 Upper bound peak_megabytes_allocated: 1375 Actual peak_megabytes_allocated: 1397 bytes allocated value is too high: Expected bytes allocated: 25990254632 +/-10% Lower bound bytes allocated: 23391229168 Upper bound bytes allocated: 28589280096 Actual bytes allocated: 28680445952 *** unexpected failure for haddock.compiler(normal) =====> T3064(normal) 2480 of 3806 [0, 3, 0] cd ./perf/compiler && '/home/smarlow/ghc/bindisttest/install dir/bin/ghc' -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3064.hs +RTS -V0 -tT3064.comp.stats --machine-readable -RTS >T3064.comp.stderr 2>&1 max_bytes_used value is too high: Expected max_bytes_used: 12000480 +/-20% Lower bound max_bytes_used: 9600384 Upper bound max_bytes_used: 14400576 Actual max_bytes_used: 15258696 peak_megabytes_allocated value is too high: Expected peak_megabytes_allocated: 30 +/-20% Lower bound peak_megabytes_allocated: 24 Upper bound peak_megabytes_allocated: 36 Actual peak_megabytes_allocated: 37 *** unexpected failure for T3064(normal)