Threadscope reporting that nothing is happening (MUT or GC) for ~2 seconds

Patrick Palka patrick at
Tue Jul 30 21:34:49 CEST 2013


I'm analyzing the performance of my parallel --make branch of GHC ( if anyone is interested)
by compiling the Cabal repository in parallel, using two capabilities.

I'm seeing very strange results from Threadscope: at some point during the
compile, absolutely no work is being performed on any HEC for about 2
seconds. How do I interpret this kind of behavior? What does it mean?

Relevant screenshot:

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