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Diffstat (limited to 'system/doc')
| -rw-r--r-- | system/doc/efficiency_guide/myths.xml | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/system/doc/efficiency_guide/myths.xml b/system/doc/efficiency_guide/myths.xml index 7e2f3c8465..d6cb27ddf0 100644 --- a/system/doc/efficiency_guide/myths.xml +++ b/system/doc/efficiency_guide/myths.xml @@ -24,7 +24,7 @@ The Initial Developer of the Original Code is Ericsson AB. </legalnotice> - <title>The Six Myths of Erlang Performance</title> + <title>The Seven Myths of Erlang Performance</title> <prepared>Bjorn Gustavsson</prepared> <docno></docno> <date>2007-11-10</date> @@ -175,5 +175,23 @@ vanilla_reverse([], Acc) -> <p>That was once true, but from R6B the BEAM compiler can see that a variable is not used.</p> </section> + + <section> + <title>Myth: A NIF Always Speeds Up Your Program</title> + + <p>Rewriting Erlang code to a NIF to make it faster should be + seen as a last resort. It is only guaranteed to be dangerous, + but not guaranteed to speed up the program.</p> + + <p>Doing too much work in each NIF call will + <seealso marker="erts:erl_nif#WARNING">degrade responsiveness + of the VM</seealso>. Doing too little work may mean that + the gain of the faster processing in the NIF is eaten up by + the overhead of calling the NIF and checking the arguments.</p> + + <p>Be sure to read about + <seealso marker="erts:erl_nif#lengthy_work">Long-running NIFs</seealso> + before writing a NIF.</p> + </section> </chapter> |