Issue #5995 has been updated by Masaki Matsushita.


=begin
>How much OSs do you tested?

I have tested on the only platform because I don't have root authority to execute "sudo sysctl -w vm.drop_caches=1" except the one.
I'm sorry.

I ran the test again and the following is average real time of 10 times:

 r34599: 0.3800858
 proposal: 0.2377475

Infomation about my environment.

 % uname -mrsvo
 Linux 3.0.0-15-server #26-Ubuntu SMP Fri Jan 20 19:07:39 UTC 2012 x86_64 GNU/Linux

 % lsb_release  -a
 LSB Version:    core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch
 Distributor ID: Ubuntu
 Description:    Ubuntu 11.10
 Release:        11.10
 Codename:       oneiric
 
 
=end
----------------------------------------
Feature #5995: calling io_advise_internal() in read_all()
https://bugs.ruby-lang.org/issues/5995

Author: Masaki Matsushita
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 


=begin
I propose to call io_advise_internal() in read_all().
It will increase performance.

I created a dummy file:
 dd if=/dev/zero of=dummy bs=1M count=100

Then, I ran the following:

 require 'benchmark'
 
 Benchmark.bm do |x|
   x.report do
     f = File.open("dummy") # dummy file(about 100MB )
     f.read
   end
 end

I freed page cache before each test:
 sudo sysctl -w vm.drop_caches=1

results on Ubuntu 11.10(3.0.0-15-server):

r34462:

 user     system      total        real
   0.050000   0.220000   0.270000 (  0.356033)
 
       user     system      total        real
   0.050000   0.190000   0.240000 (  0.332243)

       user     system      total        real
   0.060000   0.210000   0.270000 (  0.347758)

patched ruby:

 user     system      total        real
   0.030000   0.130000   0.160000 (  0.225866)

       user     system      total        real
   0.040000   0.170000   0.210000 (  0.250172)

       user     system      total        real
   0.040000   0.150000   0.190000 (  0.254654)

It shows the patch increases performance.
=end


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