HLT1 profile has large "anon" chunk
See e.g., this
The "anon" chunk is pretty much the contribution of the PrVeloUT
and my best guess is that the PrVeloUT
algorithm just has too many very large stack allocations. (Perf profiling can only collect stack frames up to a max size ~64kB, so call stack unrolling fails if all of this stack is swamped by stack variables)
I've fixed similar problems before in lhcb/Rec!2587 (merged) and lhcb/Rec!2593 (merged)
I probably won't have time to look into this in detail before I'm gone, but wanted to leave a pointer if someone would like to fix this in the future.
fyi: @decianm