Mail Archives: djgpp/2004/03/29/00:01:11
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| From: | "Alex Vinokur" <alexvn AT foot DOT com>
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| Newsgroups: | comp.lang.c++,borland.public.cppbuilder.language.cpp,comp.os.msdos.djgpp,gnu.g++.help,microsoft.public.vc.language
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| Subject: | Re: efficiency in copying files
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| Followup-To: | comp.lang.c++
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| Date: | Mon, 29 Mar 2004 06:49:13 +0300
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| Lines: | 503
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| Message-ID: | <c489sa$2fstv9$1@ID-79865.news.uni-berlin.de>
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| References: | <ba2f9c57 DOT 0403241049 DOT 76634d40 AT posting DOT google DOT com> <40622d09$0$11742$3b214f66 AT aconews DOT univie DOT ac DOT at>
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| To: | djgpp AT delorie DOT com
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"Christoph Rabel" <odie AT hal9000 DOT vc-graz DOT ac DOT at> wrote in message news:40622d09$0$11742$3b214f66 AT aconews DOT univie DOT ac DOT at...
> fabio de francesco wrote:
> >
> > My configuration is linux2.6.4, gcc3.2.3, libc2.3.2 and stdlibc++3.0.
> >
> > I have some problems in a simple copy from a 2795811 byte long binary
> > file to a new one.
> > In the following you can find a C program (ref.1) that accomplishes
> > that task in msec.50 (average time of 10 different executions).
> >
> > On the same computer and configuration I try to do the same with a
> > similar program in C++ (ref.2), but the task is done in an average of
> > msec.120.
> > That is an average of 140% more execution time.
> >
> > What am I missing? How can I write a simple C++ program that can do
> > the same task as the original C program with the same efficency?
>
> Now, there is a overhead for using streams instead of the
> old C functions. But, as I recall streams are very slow with
> gcc 3.x and this behaviour is considered a bug.
>
[snip]
Here are comparative performance of various methods of copying files in C and C++.
Copying files : input to output
===============================
C/C++ Performance Tests
=======================
Using C/C++ Program Perfometer
http://sourceforge.net/projects/cpp-perfometer
http://alexvn.freeservers.com/s1/perfometer.html
Environment
-----------
Windows 2000 Professional
Intel(R) Celeron(R) CPU 1.70 GHz
Compilers
---------
* GNU g++ 3.3.1 (cygwin); DLLs : ctgwin1.dll, kernel32.dll, ntdll.dll
* GNU g++ 3.3.1 (mingw); DLLs : msvcrt.dll, kernel32.dll, ntdll.dll
* GNU g++ 3.3.2 (djgpp); DLLs : No
* Microsoft C++ 13.00.9466; DLLs : kernel32.dll, ntdll.dll
* Borland C++ 5.5.1; DLLs : kernel32.dll, ntdll.dll, user32.dll, gdi32.dll
Testsuites
----------
C-1 : Functions getc() and putc()
C-2 : Functions fgetc() and fputc()
C-3 : Functions fread() and fwrite()
CPP-1 : Operators >> and <<
CPP-2 : Methods get() and put()
CPP-3 : Methods sbumpc() and sputc()
CPP-4 : Method sbumpc() and operator <<
CPP-5 : Method rdbuf() and operator <<
CPP-6 : Methods read() and write() with const buffer
CPP-7 : Methods read() and write() with max buffer
#################################################
Stream I/O performance tests below are based
on the article "Stream I/O"
presented at http://www.glenmccl.com/strm_cmp.htm
by Glen McCluskey & Associates LLC
#################################################
===================== Methods of copying : BEGIN =====================
ifstream in_fs;
ofstream out_fs;
FILE* in_fp;
FILE* out_fp;
char ch;
int ich;
char buf[4096];
size_t nread;
char* mbuf = new char [file_size];
### Method C-1 : Functions getc() and putc()
-----------------------------------------------------
while ((ich = getc(in_fp)) != EOF) putc(ich, out_fp);
-----------------------------------------------------
### Method C-2 : Functions fgetc() and fputc()
-------------------------------------------------------
while ((ich = fgetc(in_fp)) != EOF) fputc(ich, out_fp);
-------------------------------------------------------
### Method C-3 : Functions fread() and fwrite()
-------------------------------------------------------
while ((nread = fread(buf, sizeof(char), sizeof(buf), in_fp)) > 0)
{
fwrite(buf, sizeof(char), nread, out_fp);
}
-------------------------------------------------------
### Method CPP-1 : Operators >> and <<
---------------------------------
in_fs.unsetf(ios::skipws);
while (in_fs >> ch) out_fs << ch;
---------------------------------
### Method CPP-2 : Methods get() and put()
-------------------------------------
while (in_fs.get(ch)) out_fs.put(ch);
-------------------------------------
### Method CPP-3 : Methods sbumpc() and sputc()
------------------------------------------------------------------------
while ((ch = in_fs.rdbuf()->sbumpc()) != EOF) out_fs.rdbuf()->sputc(ch);
------------------------------------------------------------------------
### Method CPP-4 : Method sbumpc() and operator <<
-------------------------------
ch = in_fs.rdbuf()->sbumpc();
out_fs << ch;
while (ch != EOF)
{
out_fs << in_fs.rdbuf();
ch = in_fs.rdbuf()->sbumpc();
}
-------------------------------
### Method CPP-5 : Method rdbuf() and operator <<
------------------------
out_fs << in_fs.rdbuf();
------------------------
### Method CPP-6 : Methods read() and write() with const buffer
------------------------
while (!in_fs.eof())
{
in_fs.read (buf, sizeof(buf));
out_fs.write (buf,in_fs.gcount());
}
------------------------
### Method CPP-7 : Methods read() and write() with max buffer
------------------------
in_fs.read (mbuf, file_size);
out_fs.write (mbuf, file_size);
------------------------
===================== Methods of copying : END =======================
================ Performance tests : BEGIN ================
#==========================================================
# Comparison : copying files : input to output
#----------------------------------------------------------
# Resource Name : CPU-time used
# Total repetitions : 1000
# Performance metrics : milliseconds / 100 repetitions
#==========================================================
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.1 (cygwin)
Optimization : No
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 4 | 11 | 85 |
| C-2 | Functions fgetc() and fputc() | 4 | 11 | 88 |
| C-3 | Functions fread() and fwrite() | 4 | 9 | 69 |
| | | | | |
| CPP-1 | Operators >> and << | 43 | 384 | 3691 |
| CPP-2 | Methods get() and put() | 25 | 196 | 1866 |
| CPP-3 | Methods sbumpc() and sputc() | 8 | 23 | 195 |
| CPP-4 | Method sbumpc() and operator << | 7 | 12 | 80 |
| CPP-5 | Method rdbuf() and operator << | 7 | 11 | 78 |
| CPP-6 | Methods read() and write() with const buffer | 7 | 11 | 80 |
| CPP-7 | Methods read() and write() with max buffer | 7 | 11 | 69 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.1 (cygwin)
Optimization : O2
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 5 | 10 | 91 |
| C-2 | Functions fgetc() and fputc() | 5 | 11 | 94 |
| C-3 | Functions fread() and fwrite() | 5 | 9 | 71 |
| | | | | |
| CPP-1 | Operators >> and << | 45 | 399 | 3775 |
| CPP-2 | Methods get() and put() | 26 | 216 | 1913 |
| CPP-3 | Methods sbumpc() and sputc() | 7 | 21 | 169 |
| CPP-4 | Method sbumpc() and operator << | 7 | 13 | 93 |
| CPP-5 | Method rdbuf() and operator << | 7 | 13 | 89 |
| CPP-6 | Methods read() and write() with const buffer | 7 | 13 | 85 |
| CPP-7 | Methods read() and write() with max buffer | 7 | 13 | 83 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.1 (mingw)
Optimization : No
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 3 | 7 | 66 |
| C-2 | Functions fgetc() and fputc() | 4 | 28 | 276 |
| C-3 | Functions fread() and fwrite() | 2 | 3 | 24 |
| | | | | |
| CPP-1 | Operators >> and << | 9 | 69 | 671 |
| CPP-2 | Methods get() and put() | 7 | 40 | 328 |
| CPP-3 | Methods sbumpc() and sputc() | 4 | 14 | 108 |
| CPP-4 | Method sbumpc() and operator << | 4 | 6 | 38 |
| CPP-5 | Method rdbuf() and operator << | 4 | 6 | 38 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 6 | 39 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 5 | 37 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.1 (mingw)
Optimization : O2
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 2 | 5 | 36 |
| C-2 | Functions fgetc() and fputc() | 4 | 28 | 237 |
| C-3 | Functions fread() and fwrite() | 2 | 4 | 20 |
| | | | | |
| CPP-1 | Operators >> and << | 9 | 65 | 545 |
| CPP-2 | Methods get() and put() | 6 | 37 | 304 |
| CPP-3 | Methods sbumpc() and sputc() | 4 | 12 | 98 |
| CPP-4 | Method sbumpc() and operator << | 4 | 6 | 37 |
| CPP-5 | Method rdbuf() and operator << | 3 | 5 | 37 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 6 | 38 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 5 | 38 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.2 (djgpp)
Optimization : No
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 7 | 19 | 77 |
| C-2 | Functions fgetc() and fputc() | 11 | 18 | 86 |
| C-3 | Functions fread() and fwrite() | 9 | 12 | 38 |
| | | | | |
| CPP-1 | Operators >> and << | 18 | 54 | 435 |
| CPP-2 | Methods get() and put() | 18 | 32 | 200 |
| CPP-3 | Methods sbumpc() and sputc() | 13 | 23 | 116 |
| CPP-4 | Method sbumpc() and operator << | 14 | 15 | 49 |
| CPP-5 | Method rdbuf() and operator << | 15 | 13 | 47 |
| CPP-6 | Methods read() and write() with const buffer | 16 | 16 | 51 |
| CPP-7 | Methods read() and write() with max buffer | 13 | 15 | 52 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : GNU g++ 3.3.2 (djgpp)
Optimization : O2
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 11 | 18 | 77 |
| C-2 | Functions fgetc() and fputc() | 11 | 16 | 78 |
| C-3 | Functions fread() and fwrite() | 11 | 12 | 44 |
| | | | | |
| CPP-1 | Operators >> and << | 22 | 55 | 430 |
| CPP-2 | Methods get() and put() | 19 | 33 | 224 |
| CPP-3 | Methods sbumpc() and sputc() | 16 | 22 | 107 |
| CPP-4 | Method sbumpc() and operator << | 16 | 16 | 49 |
| CPP-5 | Method rdbuf() and operator << | 15 | 16 | 49 |
| CPP-6 | Methods read() and write() with const buffer | 15 | 16 | 53 |
| CPP-7 | Methods read() and write() with max buffer | 14 | 16 | 55 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : Microsoft C++ 13.00.9466
Optimization : Od
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 3 | 8 | 73 |
| C-2 | Functions fgetc() and fputc() | 3 | 10 | 90 |
| C-3 | Functions fread() and fwrite() | 3 | 5 | 29 |
| | | | | |
| CPP-1 | Operators >> and << | 16 | 131 | 1163 |
| CPP-2 | Methods get() and put() | 16 | 129 | 1196 |
| CPP-3 | Methods sbumpc() and sputc() | 5 | 27 | 239 |
| CPP-4 | Method sbumpc() and operator << | 8 | 51 | 456 |
| CPP-5 | Method rdbuf() and operator << | 8 | 51 | 476 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 6 | 34 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 6 | 34 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : Microsoft C++ 13.00.9466
Optimization : O2
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 2 | 5 | 39 |
| C-2 | Functions fgetc() and fputc() | 2 | 7 | 58 |
| C-3 | Functions fread() and fwrite() | 2 | 4 | 28 |
| | | | | |
| CPP-1 | Operators >> and << | 15 | 122 | 1173 |
| CPP-2 | Methods get() and put() | 14 | 124 | 1121 |
| CPP-3 | Methods sbumpc() and sputc() | 5 | 27 | 197 |
| CPP-4 | Method sbumpc() and operator << | 8 | 58 | 426 |
| CPP-5 | Method rdbuf() and operator << | 8 | 55 | 470 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 6 | 33 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 5 | 33 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : Microsoft C++ 13.00.9466
Optimization : Ox
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 2 | 5 | 35 |
| C-2 | Functions fgetc() and fputc() | 2 | 6 | 51 |
| C-3 | Functions fread() and fwrite() | 2 | 4 | 25 |
| | | | | |
| CPP-1 | Operators >> and << | 14 | 111 | 1200 |
| CPP-2 | Methods get() and put() | 13 | 105 | 1056 |
| CPP-3 | Methods sbumpc() and sputc() | 5 | 22 | 220 |
| CPP-4 | Method sbumpc() and operator << | 7 | 44 | 417 |
| CPP-5 | Method rdbuf() and operator << | 7 | 44 | 415 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 5 | 30 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 5 | 30 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : Borland C++ 5.5.1
Optimization : Od
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 2 | 5 | 51 |
| C-2 | Functions fgetc() and fputc() | 3 | 22 | 216 |
| C-3 | Functions fread() and fwrite() | 2 | 3 | 24 |
| | | | | |
| CPP-1 | Operators >> and << | 8 | 47 | 456 |
| CPP-2 | Methods get() and put() | 7 | 43 | 361 |
| CPP-3 | Methods sbumpc() and sputc() | 4 | 12 | 88 |
| CPP-4 | Method sbumpc() and operator << | 4 | 11 | 82 |
| CPP-5 | Method rdbuf() and operator << | 4 | 11 | 80 |
| CPP-6 | Methods read() and write() with const buffer | 4 | 10 | 73 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 10 | 66 |
--------------------------------------------------------------------------------
--- Summary test results ---
============================
Compiler : Borland C++ 5.5.1
Optimization : O2
============================
--------------------------------------------------------------------------------
| | | CPU time used for |
| No. | Method | file size |
| | |-----------------------|
| | | 100 | 1000 | 10000 |
|------------------------------------------------------------------------------|
| C-1 | Functions getc() and putc() | 2 | 5 | 36 |
| C-2 | Functions fgetc() and fputc() | 4 | 28 | 237 |
| C-3 | Functions fread() and fwrite() | 2 | 4 | 20 |
| | | | | |
| CPP-1 | Operators >> and << | 9 | 65 | 545 |
| CPP-2 | Methods get() and put() | 6 | 37 | 304 |
| CPP-3 | Methods sbumpc() and sputc() | 4 | 12 | 98 |
| CPP-4 | Method sbumpc() and operator << | 4 | 6 | 37 |
| CPP-5 | Method rdbuf() and operator << | 3 | 5 | 37 |
| CPP-6 | Methods read() and write() with const buffer | 3 | 6 | 38 |
| CPP-7 | Methods read() and write() with max buffer | 3 | 5 | 38 |
--------------------------------------------------------------------------------
================ Performance tests : END ==================
==============================================
Alex Vinokur
mailto:alexvn AT connect DOT to
http://mathforum.org/library/view/10978.html
==============================================
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