very slow progress

[git.ikiwiki.info.git] / doc / tips / optimising_ikiwiki.mdwn

diff --git a/doc/tips/optimising_ikiwiki.mdwn b/doc/tips/optimising_ikiwiki.mdwn
index e3973733fba4de9754306b80bd22fff8f6a1370b..caed75ba6fb18356c37dbdf249c6e815a4fdf88c 100644 (file)
--- a/doc/tips/optimising_ikiwiki.mdwn
+++ b/doc/tips/optimising_ikiwiki.mdwn
@@ -34,10 +34,18 @@ when their wiki was small, and found it got slower as they added pages.
 
 ## use the latest version
 
-If your version of ikiwiki is not [[!verison]], try upgrading. New
+If your version of ikiwiki is not [[!version]], try upgrading. New
 optimisations are frequently added to ikiwiki, some of them yielding
 *enormous* speed increases.
 
+## run ikiwiki in verbose mode
+
+Try changing a page, and run ikiwiki with `-v` so it will tell you
+everything it does to deal with that changed page. Take note of
+which other pages are rebuilt, and which parts of the build take a long
+time. This can help you zero in on individual pages that contain some of
+the expensive things listed below. 
+
 ## expensive inlines
 
 Do you have an archive page for your blog that shows all posts, 
@@ -64,7 +72,7 @@ smaller.
        
        \[[!inline pages="blog/* and link(tag)" show=0 archive=yes quick=yes]]
 
-Only downsides: This won't show titles set by the [[!ikiwiki/directive/meta]]
+Only downsides: This won't show titles set by the [[ikiwiki/directive/meta]]
 directive. And there's no RSS feed for users to use -- but if this page
 is only for the archives or tag for your blog, users should be subscribing
 to the blog's main page's RSS feed instead.
@@ -85,7 +93,7 @@ The resulting html file might get big and expensive to generate as you
 keep adding pages.
 
 First, consider removing the "show=title". Then the map will not show page
-titles set by the [[!ikiwiki/directive/meta]] directive -- but will also
+titles set by the [[ikiwiki/directive/meta]] directive -- but will also
 only need to be generated when pages are added or removed, not for every
 page change.
 
@@ -140,6 +148,21 @@ That is accomplished as follows:
 Be aware that the [[plugins/search]] plugin has to update the search index
 whenever any page is changed. This can slow things down somewhat.
 
+## profiling
+
+If you have a repeatable change that ikiwiki takes a long time to build,
+and none of the above help, the next thing to consider is profiling
+ikiwiki. 
+
+The best way to do it is:
+
+* Install [[!cpan Devel::NYTProf]]
+* `PERL5OPT=-d:NYTProf`
+* `export PER5OPT`
+* Now run ikiwiki as usual, and it will generate a `nytprof.out` file.
+* Run `nytprofhtml` to generate html files.
+* Those can be examined to see what parts of ikiwiki are being slow.
+
 ## scaling to large numbers of pages
 
 Finally, let's think about how huge number of pages can affect ikiwiki.
@@ -153,7 +176,7 @@ Finally, let's think about how huge number of pages can affect ikiwiki.
   quickly, but still, lots more pages will make PageSpecs more expensive.
 
 * The backlinks calculation has to consider every link on every page
-  in the wiki. (In practice, most pages only like to at most a few dozen
+  in the wiki. (In practice, most pages only link to at most a few dozen
   other pages, so this is not a `O(N^2)`, but closer to `O(N)`.)
 
 * Ikiwiki also reads and writes an `index` file, which contains information