我正在使用基于ruby-prof的rspec-prof来描述需要相当长时间的规范。但是，我无法解释我得到的结果，因为它们报告的是负面时间。我是否正确使用rspec-prof / ruby-prof？这是一个错误吗？
zkhan@ubuntu:~/rails_projects/gamestory_app$ rspec spec/controllers/games_controller_spec.rb
Rack::File headers parameter replaces cache_control after Rack 1.5.
.#<RSpec::Core::Example:0xad11370>
Thread ID: 75909140
Total: -0.650803
Sort by: self_time
%self total self wait child calls name
166.30 -6.402 -1.082 0.000 -5.320 212670 ActiveRecord::AttributeMethods::Dirty#write_attribute
335.29 -0.278 -2.182 0.000 1.904 425424 ActiveRecord::AttributeMethods#column_for_attribute
506.56 1.807 -3.297 0.000 5.103 170406 ActiveRecord::AttributeMethods#clone_attribute_value
517.51 -1.086 -3.368 0.000 2.282 51106 *Hash#each
580.84 -3.780 -3.780 0.000 0.000 79648 String#=~
597.22 -3.559 -3.887 0.000 0.327 114325 ActiveRecord::AttributeMethods#has_attribute?
600.60 -3.909 -3.909 0.000 0.000 162452 Thread#[]
601.95 -3.249 -3.917 0.000 0.669 46380 ActiveRecord::AttributeMethods#respond_to?
607.83 -1.781 -3.956 0.000 2.175 76529 *Array#map
627.42 -3.986 -4.083 0.000 0.097 93932 Fixnum#==
629.84 1.281 -4.099 0.000 5.380 69849 <Class::ActiveRecord::Base>#connection
641.72 -3.727 -4.176 0.000 0.449 8193 Logger::Formatter#call
645.68 -3.893 -4.202 0.000 0.309 16428 <Class::Time>#time_with_datetime_fallback
650.89 -4.229 -4.236 0.000 0.007 3486 <Class::Time>#_load_without_zone
653.77 -4.223 -4.255 0.000 0.032 7122 ActiveSupport::TimeWithZone#respond_to?
654.19 -4.116 -4.257 0.000 0.142 9510 EnumeratedAttribute::Attribute::AttributeDescriptor#allows_value?
1236.59 -4.752 -8.048 0.000 3.296 58802 ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#quote
2894.34 -18.465 -18.836 0.000 0.372 21840 BigDecimal#==
* indicates recursively called methods
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Finished in 2 minutes 24.62 seconds
2 examples, 0 failures
Randomized with seed 63912