HEAD: Deterioration in ByteString I/O

[Simon Peyton-Jones]

|  > ghc-6.12.3:
|  >       89,330,672 bytes allocated in the heap
|  >           15,092 bytes copied during GC
|  >           35,980 bytes maximum residency (1 sample(s))
|  >           29,556 bytes maximum slop
|  >                2 MB total memory in use (0 MB lost due to fragmentation)
|  >
|  > ghc-6.13.20100831:
|  >      475,305,720 bytes allocated in the heap
|  >           89,272 bytes copied during GC
|  >           68,860 bytes maximum residency (1 sample(s))
|  >           29,444 bytes maximum slop
|  >                2 MB total memory in use (0 MB lost due to fragmentation)
|  
|  Can you put your benchmark code somewhere?  Likely a GHC regression.

Indeed bad. If someone could characterise the regression more precisely (e.g. "fusion isn't happening here") that would be jolly helpful. 

Simon