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planner: remove Bühlmann factor cache

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The Bühlmann factors were cached in a thread-safe hashmap. It seemed
somewhat dubious that entering a critical section and doing a hash-lookup
would be significantly faster than a simple exp() call.

Indeed, in a very cache friendly test (16 entries, tight loop) calling the
factor() function 32 000 000 times from a different translation units we get:
  - with cache: 604 ms
  - without cache: 266 ms
Therefore, remove the cache. Given that 32 000 000 calls take only 266 ms,
it appears not sensible to try to optimize this function anyway.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2020-05-05 22:24:50 +02:00 • committed by Robert C. Helling
parent f37f428762
commit 123937901f
3 changed files with 6 additions and 47 deletions
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core/qthelper.h
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@ -146,8 +146,6 @@ const char *subsurface_user_agent();
enum deco_mode decoMode();
int parse_seabear_header(const char *filename, char **params, int pnr);
char *get_current_date();
double cache_value(int tissue, int timestep, enum inertgas gas);
void cache_insert(int tissue, int timestep, enum inertgas gas, double value);
void print_qt_versions();
void lock_planner();
void unlock_planner();