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Add some basic profiling support to the evaluator

Setting the environment variable NIX_COUNT_CALLS to 1 enables some
basic profiling in the evaluator.  It will count calls to functions
and primops as well as evaluations of attributes.

For example, to see where evaluation of a NixOS configuration spends
its time:

$ NIX_SHOW_STATS=1 NIX_COUNT_CALLS=1 ./src/nix-instantiate/nix-instantiate '<nixos>' -A system --readonly-mode
...
calls to 39 primops:
    239532 head
    233962 tail
    191252 hasAttr
...
calls to 1595 functions:
    224157 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:19'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:14'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:10'
...
evaluations of 7088 attributes:
    167377 undefined position
    132459 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:119:41'
     47322 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:13:21'
...
This commit is contained in:
Eelco Dolstra 2012-08-12 23:29:28 -04:00
parent 325d1cfebf
commit e82767910c
5 changed files with 65 additions and 4 deletions

View file

@ -17,6 +17,9 @@ namespace nix {
#define foreach(it_type, it, collection) \
for (it_type it = (collection).begin(); it != (collection).end(); ++it)
#define foreach_reverse(it_type, it, collection) \
for (it_type it = (collection).rbegin(); it != (collection).rend(); ++it)
/* Return an environment variable. */
string getEnv(const string & key, const string & def = "");