76-fold regression GHC 7.10->7.11 in T9961 byte-allocation

[Simon Peyton Jones]

Aha.  I believe that the ghc-7.10 branch simply doesn't have the source file
	testsuite/tests/perf/compiler/T9961.hs
but all.T still runs the test.  So we get "does not exist: T9961.hs", and of course very little allocation.

Austin or Herbert, could you add T9961.hs to the 7.10 branch?

Simon

|  -----Original Message-----
|  From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of
|  Herbert Valerio Riedel
|  Sent: 30 January 2015 11:03
|  To: ghc-devs
|  Subject: 76-fold regression GHC 7.10->7.11 in T9961 byte-allocation
|  
|  Hello *,
|  
|  I noticed something odd while validating the GHC 7.10 branch:
|  
|    bytes allocated value is too low:
|    (If this is because you have improved GHC, please
|    update the test so that GHC doesn't regress again)
|        Expected    T9961(normal) bytes allocated: 772510192 +/-5%
|        Lower bound T9961(normal) bytes allocated: 733884682
|        Upper bound T9961(normal) bytes allocated: 811135702
|        Actual      T9961(normal) bytes allocated:   9766160
|        Deviation   T9961(normal) bytes allocated:     -98.7 %
|    *** unexpected stat test failure for T9961(normal)
|  
|  
|  ...then I also ran ./validate against today's GHC HEAD, and re-ran the
|  T9961 test:
|  
|      Expected    T9961(normal) bytes allocated: 772510192 +/-5%
|      Lower bound T9961(normal) bytes allocated: 733884682
|      Upper bound T9961(normal) bytes allocated: 811135702
|      Actual      T9961(normal) bytes allocated: 748225848
|      Deviation   T9961(normal) bytes allocated:      -3.1 %
|  
|  
|  I'm not sure if it's just the test-case being broken, or there's
|  something real regression between 7.10 and HEAD...
|  
|  However, I don't have time to investigate this.
|  
|  Cheers,
|    hvr
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