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authorEelco Dolstra <eelco.dolstra@logicblox.com>2012-08-13T04·28-0400
committerEelco Dolstra <eelco.dolstra@logicblox.com>2012-08-13T04·28-0400
commit4ccd48ce2478cbe1263605838969f89d5b745f0a (patch)
treefdd0e61026350faf816cf3fe6fba3da6ac1b8ebf /src/libexpr/eval.cc
parent62f72eb9e1a4421a9d4ea3e06f467e49869c0e51 (diff)
Add a "filter" primop
Evaluation of a NixOS configuration spends quite a lot of time in the
"filter" function in Nixpkgs.  As implemented in Nixpkgs, this is a
O(n^2) operation, so it's a good candidate for providing a more
efficient (i.e. primop) implementation.  Using it gives a ~10% speed
increase and a significant reduction in the number of evaluations.

Statistics before (on a NixOS system config):

  time elapsed: 1.3258
  size of a value: 24
  environments allocated: 1980939 (50127080 bytes)
  list elements: 14679308 (117434464 bytes)
  list concatenations: 50828
  values allocated: 2098938 (50374512 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18271
  number of thunks: 1645752
  number of thunks avoided: 1921196
  number of attr lookups: 430798
  number of primop calls: 838807
  number of function calls: 1930107

Statistics after:

  time elapsed: 1.17982
  size of a value: 24
  environments allocated: 1543334 (39624560 bytes)
  list elements: 9612638 (76901104 bytes)
  list concatenations: 37434
  values allocated: 1854933 (44518392 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18272
  number of thunks: 1392467
  number of thunks avoided: 1507311
  number of attr lookups: 430801
  number of primop calls: 691600
  number of function calls: 1492502
Diffstat (limited to 'src/libexpr/eval.cc')
-rw-r--r--src/libexpr/eval.cc2
1 files changed, 1 insertions, 1 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index a1a227c8a3e0..871dfa64cbe3 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -724,7 +724,7 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
     }
     
     if (fun.type != tLambda)
-        throwTypeError("attempt to call something which is neither a function nor a primop (built-in operation) but %1%",
+        throwTypeError("attempt to call something which is not a function but %1%",
             showType(fun));
 
     unsigned int size =