[#42344] [ruby-trunk - Feature #5964][Open] Make Symbols an Alternate Syntax for Strings — Tom Wardrop <tom@...>

23 messages 2012/02/03

[#42443] [ruby-trunk - Bug #5985][Open] miniruby skews "make benchmark" results — Eric Wong <normalperson@...>

21 messages 2012/02/08

[#42444] [ruby-trunk - Bug #5986][Open] Segmentation Fault — Luis Matta <levmatta@...>

16 messages 2012/02/08

[#42471] [ruby-trunk - Feature #5995][Open] calling io_advise_internal() in read_all() — Masaki Matsushita <glass.saga@...>

20 messages 2012/02/10

[#42560] [ruby-trunk - Bug #6011][Open] ruby-1.9.3-p0/lib/webrick/utils.rb:184: [BUG] Segmentation fault — Vit Ondruch <v.ondruch@...>

12 messages 2012/02/13

[#42579] [ruby-trunk - Bug #6012][Open] Proc#source_location also return the column — Roger Pack <rogerpack2005@...>

14 messages 2012/02/14

[#42685] [ruby-trunk - Bug #6036][Open] Test failures in Fedora Rawhide/17 — Bohuslav Kabrda <bkabrda@...>

14 messages 2012/02/16

[#42697] [ruby-trunk - Bug #6040][Open] Transcoding test failure: Big5 to UTF8 not defined (MinGW) — Luis Lavena <luislavena@...>

10 messages 2012/02/16

[#42813] [ruby-trunk - Feature #6065][Open] Allow Bignum marshalling/unmarshalling from C API — Martin Bosslet <Martin.Bosslet@...>

22 messages 2012/02/23

[#42815] [ruby-trunk - Bug #6066][Open] Fix "control may reach end of non-void function" warnings for clang — Eric Hodel <[email protected]>

15 messages 2012/02/23

[#42857] [ruby-trunk - Feature #6074][Open] Allow alias arguments to have a comma — Thomas Sawyer <transfire@...>

20 messages 2012/02/24

[#42891] [ruby-trunk - Feature #6083][Open] Hide a Bignum definition — Koichi Sasada <redmine@...>

23 messages 2012/02/25

[#42906] [ruby-trunk - Bug #6085][Open] Treatment of Wrong Number of Arguments — Marc-Andre Lafortune <ruby-core@...>

14 messages 2012/02/25

[#42949] [ruby-trunk - Bug #6089][Open] Test suite fails with OpenSSL 1.0.1 — Vit Ondruch <v.ondruch@...>

13 messages 2012/02/26

[ruby-core:42683] [ruby-trunk - Feature #5995][Rejected] calling io_advise_internal() in read_all()

From: Yusuke Endoh <mame@...>
Date: 2012-02-16 12:55:43 UTC
List: ruby-core #42683
Issue #5995 has been updated by Yusuke Endoh.

Status changed from Assigned to Rejected

Hello,

There is indeed something wrong, but anyway, I agree with
kosaki's point; we cannot import the patch until we know
the exact reason why it brings performance improvement.
So please reopen this ticket if you find the reason.
(I expect kosaki-san to consider this!)


I wrote a simple C code to experiment this.  The result is
as kosaki said; when calling only one read syscall, posix_
fadvise does NOT bring performance improvement (even slower).
I really wonder why File#read becomes faster.



# using posix_fadvise
$ sudo sysctl -w vm.drop_caches=1 && time ./t dummy T
vm.drop_caches = 1
314572800

real    0m5.401s
user    0m0.000s
sys     0m0.740s


# NOT using posix_fadvise
$ sudo sysctl -w vm.drop_caches=1 && time ./t dummy F
vm.drop_caches = 1
314572800

real    0m3.967s
user    0m0.000s
sys     0m0.896s


#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>


int main(int argc, char *argv[])
{
    int fd = open(argv[1], O_RDONLY);
    char *buf;
    struct stat s;

    fstat(fd, &s);
    buf = malloc(s.st_size);

    if (argv[2][0] == 'T') {
        posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
    }

    printf("%d\n", read(fd, buf, s.st_size));

    return 0;
}

-- 
Yusuke Endoh <[email protected]>
----------------------------------------
Feature #5995: calling io_advise_internal() in read_all()
https://bugs.ruby-lang.org/issues/5995

Author: Masaki Matsushita
Status: Rejected
Priority: Normal
Assignee: Motohiro KOSAKI
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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