normal	2017-05-05 01:47:17 +0900 (Fri, 05 May 2017)

  New Revision: 58571

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=58571

  Log:
    benchmark/bm_vm_thread_pass_flood.rb: add comment
    
    I was about to write off this benchmark while working on GVL
    improvements on multi-core systems.
    
    However I noticed it exposes a weakness in my work-in-progress
    code when I tested on an old single CPU system.  Further testing
    reveals setting CPU affinity ("schedtool -a 0x1" on Linux) on a
    modern multi-core system is enough to reproduce the problem
    exposed by this benchmark.

  Modified files:
    trunk/benchmark/bm_vm_thread_pass_flood.rb
Index: benchmark/bm_vm_thread_pass_flood.rb
===================================================================
--- benchmark/bm_vm_thread_pass_flood.rb	(revision 58570)
+++ benchmark/bm_vm_thread_pass_flood.rb	(revision 58571)
@@ -1,3 +1,5 @@ https://github.com/ruby/ruby/blob/trunk/benchmark/bm_vm_thread_pass_flood.rb#L1
+# n.b. this is a good test for GVL when pinned to a single CPU
+
 1000.times{
   Thread.new{loop{Thread.pass}}
 }

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