Consider the attached test case. The expected output is the that of the prof way, while for profasm and profthreaded, I get this result:

=====> callstack003(profthreaded) 19 of 21 [0, 1, 0]
cd . && '/home/jojo/dokumente/Uni/info/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -o callstack003 callstack003.hs -O -prof -auto-all -threaded -fprof-auto-calls -fno-full-laziness -fno-state-hack  >callstack003.comp.stderr 2>&1
cd . && ./callstack003  +RTS -p -RTS  </dev/null >callstack003.run.stdout 2>callstack003.run.stderr
Actual stdout output differs from expected:
--- ./callstack003.stdout	2012-09-17 11:27:02.607458948 +0200
+++ ./callstack003.run.stdout	2012-09-17 12:20:33.988109494 +0200
@@ -1,8 +1,8 @@
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:15-17)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:22-24)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:15-17)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:22-24)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:15-17)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:22-24)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:15-17)","Main.f (callstack003.hs:7:11-36)"]
-["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.doTwice (callstack003.hs:10:22-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
+["Main.CAF (<entire-module>)","Main.main (callstack003.hs:9:8-21)","Main.doTwice (callstack003.hs:10:15-24)","Main.f (callstack003.hs:7:11-36)"]
*** unexpected failure for callstack003(profthreaded)

Not sure if this really hurts anyone, and the behavior of the call stack WRT recursive calls is anyways not quite perfect yet (see #7240), this makes adding good test cases a bit difficult.