====== Profiling on Modern CPUs ======

Profiling isn't just "count instructions, look for hotspots" anymore. Between the superscalar-ness, the multi-core-ness, the shared-cache-ness, the shared-bus-ness, the hierarchical memory-ness and a lot of other -ness'es, things get a little.. special.

This is (for now) a reading list and set of notes of what I've come across whilst exploring what's going on with modern intel hardware.

===== notes =====

There are a few things to try and make .. easier to do in PMC:

  * A system overview (eg GNU/perf 'perf stat') that gives simple overviews for things like general instruction counts and efficiencies, cache thrashing, resource stalls, etc
  * Make it much easier to establish where certain classes of bottlenecks are when profiling (again - bus / cache bottlenecks, cache thrashing, resource stalls)
  * A much nicer way of summarising / analysing counters - right now it's per-CPU and on larger CPU machines this gets very unwieldy very quickly
  * A machine-summarised version of the counter output (with timestamping) so it can be fed into external processing scripts

===== reading list =====

  * http://software.intel.com/sites/products/collateral/hpc/vtune/cycle_accounting_analysis.pdf
  * https://perf.wiki.kernel.org/index.php/Tutorial
  * http://publib.boulder.ibm.com/infocenter/clresctr/vxrx/index.jsp?topic=%2Fcom.ibm.cluster.pedev.v1r2.pedev100.doc%2Fbl7ug_derivedmetricsandybridge.htm
  * http://oprofile.sourceforge.net/docs/intel-sandybridge-events.php
  * https://perf.wiki.kernel.org/index.php/Tutorial#Counting_with_perf_stat
  * http://www.bnikolic.co.uk/blog/hpc-prof-events.html
  * http://software.intel.com/sites/products/documentation/doclib/stdxe/2013/amplifierxe/win/win_reference/pmn/events/resource_stalls.html
  * http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf
  * http://www.intel.com/content/dam/www/public/us/en/documents/design-guides/xeon-e5-2600-uncore-guide.pdf
  * http://software.intel.com/sites/default/files/m/a/d/2/2/e/15529-Intel_VTune_Using.pdf
  * http://software.intel.com/en-us/tags/17380