From: Eric Wong <normalperson@...>
Date: 2011-09-19T18:11:00+09:00
Subject: [ruby-core:39623] [Ruby 1.9 - Bug #5335] [RFC/PATCH] test_old_thread_select: timing tweaks


Issue #5335 has been updated by Eric Wong.

File old_thread_select-skip-ancient-linux.patch added

While dynticks appeared in 2.6.21, I'm defining "ancient" as pre-2.6.32 since
2.6.32 is still supported and widely deployed.

(having SSL troubles with redmine, apologies if you see this twice/thrice)

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Bug #5335: [RFC/PATCH] test_old_thread_select: timing tweaks
http://redmine.ruby-lang.org/issues/5335

Author: Eric Wong
Status: Open
Priority: Normal
Assignee: Eric Wong
Category: core
Target version: 1.9.3
ruby -v: ruby 1.9.3dev (2011-09-17 revision 33290) [x86_64-linux]


I was getting timing errors and short select() timeouts on CentOS 5.6
2.6.18-238.9.1.el5xen most likely due to CONFIG_HZ=250 and the lack of dynticks,
but maybe being a Xen VM has this effect, too.

select() itself appears to just be inaccurate on this system:

	strace -e select -T ./ruby -e 'select([STDIN],nil,nil,0.001)'
	select(1, [0], NULL, NULL, {0, 1000})   = 0 (Timeout) <0.000046>

I'm not happy with timing tests, but I can't think of another way to test
functionality like this.


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