commit 12dbeb46bd34128759305c067da4b095a727ccbb
Author: Max Rottenkolber <max@mr.gy>
Date:   Wed Jul 27 02:35:01 2016 +0200

    Added blog post “Sam: a tiny, concurrent sampling profiler...”.

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+I have recently been in need of a profiler for my favorite Common Lisp
+implementation, [Clozure Common Lisp](http://ccl.clozure.com/), but sadly its
+[mechanism for generating a Lisp image for use with oprofile](http://ccl.clozure.com/docs/ccl.html#using-the-linux-oprofile-system-level-profiler)
+no longer works with recent versions of Linux/oprofile. [rme](http://www.thoughtstuff.com/)
+explained it to me in {#ccl} on Freenode:
+
+“_Recent kernels and perf versions are not fooled by our trick of making a heap
+image look sort of like an ELF file. Also, they only consider mapped memory
+from ELF files (and not just some random file, like a heap image) as a place
+where functions can reside._”
+
+That was disappointing, I had waited for the new Slackware release to get a
+compatible version of libelf, after all. I also looked into the deterministic
+profiler for CCL by Hans Huebner that lives in {contrib/}, but that one
+bit-rotted, sadly.
+
+#media Still from the 2009 movie “Moon”. The protagonist’s name is Sam as
+well.#
+sam.jpg
+
+Still, my search was not in vain. rme sent me a very helpful
+[paste](http://paste.lisp.org/display/319875), whose contents he described as
+“a crude userland-based sampling profiler”. Here is how it works: it peeks into
+the call stack of a running process repeatedly to find out which function is
+being run, and counts how often it finds the process busy with a given
+function. With the collected information it can then report an estimate of
+where time is spent.
+
+After having given some love to this tiny profiler’s report output, I figured
+why not share it for others to use, and rme kindly agreed. Meet
+[Sam](https://github.com/eugeneia/sam), it supports profiling forms as well as
+running processes, and is reasonably well
+[documented](http://mr.gy/software/sam/api.html). You can use it to profile
+arbitrary forms like this:
+
+#code#
+CL-USER> (sam:profile ()
+           (loop for i from 1 to 1e8 sum i))
+39%  CCL::>-2  <no source>
+19%  CCL::FIXNUM-SFLOAT-COMPARE  <no source>
+15%  #<Anonymous Function #x30200B10843F>  <no source>
+12%  SAM:CALL-WITH-SAMPLING  (defun call-with-sampling (fn ...
+11%  CCL::INTEGER-DECODE-SHORT-FLOAT  <no source>
+ 5%  CCL::FIXNUM-DECODE-SHORT-FLOAT  <no source>
+#
+
+…or profile a different process:
+
+#code#
+CL-USER> (sam:profile-process (fourth (all-processes)) 1)
+100%  CCL::FD-READ  <no source>
+#
+
+May the search engines index this, and spare others from repeating my search
+(but not from reading about it.) I hope Sam can be of use to you, and let me
+know if you find any bugs!