|  | How to stl library efficiently? | | |
| | | Peng Yu |  |
|  Posted: Sun Aug 10, 2008 5:49 am Post subject: How to stl library efficiently? |  |
Hi,
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
Thanks,
Peng
--
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| |
| | | Ulrich Eckhardt | |
| | Posted: Sun Aug 10, 2008 4:03 pm Post subject: Re: How to stl library efficiently? | |
Peng Yu wrote:
| Quote: | I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
|
There is also deque as possible unordered container. BTW, can you supply a
URL of mentioned discussion?
| Quote: | I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
|
It's a very obvious trick but it still applies here: profile first, optimise
later.
Lastly: the STL was in large parts incorporated into the C++ stardardlibrary
but the overlap is not 100%. I'd generally target my code at the C++
standardlibrary, the STL itself is pretty much dead nowadays.
Uli
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| |
| | | red floyd | |
| | Posted: Sun Aug 10, 2008 4:28 pm Post subject: Re: How to stl library efficiently? | |
Peng Yu wrote:
| Quote: | Hi,
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
|
Get Scott Meyer's "Effective STL".
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| |
| | | Mathias Gaunard | |
| | Posted: Sun Aug 10, 2008 4:28 pm Post subject: Re: How to stl library efficiently? | |
On 10 août, 07:49, Peng Yu <PengYu...@gmail.com> wrote:
| Quote: | I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
|
You need move semantics and in-place construction for comparable
performance.
Which are not in the current implementation.
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| |
| | | Sergey P. Derevyago | |
| | Posted: Wed Aug 13, 2008 6:24 pm Post subject: Re: How to stl library efficiently? | |
| |  | |
Peng Yu wrote:
| Quote: | I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
Sure. |
Please read "C++ multithreading: mem_pool" message:
Message-ID: <4899c3e1$0$90276$14726298@news.sunsite.dk>
LINK
-----------------------------------8<-----------------------------------
void start_std(void*)
{
list<int> lst;
for (int i=0; i<N; i++) {
for (int j=0; j<M; j++) lst.push_back(j);
for (int j=0; j<M; j++) lst.pop_front();
}
}
void start_ders(void*)
{
mem_pool mp;
stl_allocator<int> alloc(mp);
list<int, stl_allocator<int> > lst(alloc);
for (int i=0; i<N; i++) {
for (int j=0; j<M; j++) lst.push_back(j);
for (int j=0; j<M; j++) lst.pop_front();
}
}
-----------------------------------8<-----------------------------------
The table at LINK shows
that start_ders() function is tens and hundreds (!!!) of times faster:
1 CPU : 38.1
1 CPU,HT : 42.1
2 CPU,SMP: 321.6 (!!!)
2 CPU,HT : 37.0
--
With all respect, Sergey. LINK
mailto : ders at skeptik.net
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| |
| | | Peng Yu | |
| | Posted: Sun Aug 17, 2008 6:51 pm Post subject: Re: How to stl library efficiently? | |
| Quote: | The table LINK
that start_ders() function is tens and hundreds (!!!) of times faster:
|
The website you mentioned in some language rather than English (maybe
Russian). I don't understand that language. Is there an English
version for it.
Thanks,
Peng
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| |
| | | Peng Yu | |
| | Posted: Sun Aug 17, 2008 6:52 pm Post subject: Re: How to stl library efficiently? | |
| | | |
On Aug 10, 11:03 am, Ulrich Eckhardt <dooms...@knuut.de> wrote:
| Quote: | Peng Yu wrote:
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
There is also deque as possible unordered container. BTW, can you supply a
URL of mentioned discussion?
|
I came across such webpage long time back. I can recall where it is.
Sorry about that.
| Quote: | I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
It's a very obvious trick but it still applies here: profile first, optimise
later.
Lastly: the STL was in large parts incorporated into the C++ stardardlibrary
but the overlap is not 100%. I'd generally target my code at the C++
standardlibrary, the STL itself is pretty much dead nowadays.
|
I always use the following website for the documentation when I use
STL.
LINK
Where is the C++ Standard Library manual? I found this one
LINK Is it appropriate?
What is the major difference between C++ Standard Library and STL? I
usually use GCC C++ compiler. It has the complete C++ Standard
Library, right?
--
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| |
| | | Peng Yu | |
| | Posted: Sun Aug 17, 2008 6:52 pm Post subject: Re: How to stl library efficiently? | |
On Aug 10, 11:28 am, red floyd <no.spam.h...@example.com> wrote:
| Quote: | Peng Yu wrote:
Hi,
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
Get Scott Meyer's "Effective STL".
|
It seems that it is a little bit outdated. For example, it mentioned
auto_ptr, but people usually use boost::shared_ptr. I'm wondering what
are the things that have been changed since the book was written.
Thanks,
Peng
--
[ See LINK for info about ]
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| |
| | | Erik Wikström | |
| | Posted: Mon Aug 18, 2008 1:58 pm Post subject: Re: How to stl library efficiently? | |
| | | |
On 2008-08-17 20:52, Peng Yu wrote:
| Quote: | On Aug 10, 11:03 am, Ulrich Eckhardt <dooms...@knuut.de> wrote:
Peng Yu wrote:
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
There is also deque as possible unordered container. BTW, can you supply a
URL of mentioned discussion?
I came across such webpage long time back. I can recall where it is.
Sorry about that.
I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
It's a very obvious trick but it still applies here: profile first, optimise
later.
Lastly: the STL was in large parts incorporated into the C++ stardardlibrary
but the overlap is not 100%. I'd generally target my code at the C++
standardlibrary, the STL itself is pretty much dead nowadays.
I always use the following website for the documentation when I use
STL.
LINK
Where is the C++ Standard Library manual? I found this one
LINK Is it appropriate?
What is the major difference between C++ Standard Library and STL? I
usually use GCC C++ compiler. It has the complete C++ Standard
Library, right?
|
STL is the name that was used before it became part of the C++ standard,
the C++ standard library contains the STL and some other stuff (like IO
capabilities etc.), so you can say that the STL is a subset of the
standard library.
The gcc standard library implementation is probably close to complete,
you can probably find detailed information about its conformance at the
gnu site.
--
Erik Wikström
[ See LINK for info about ]
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| |
| | | Erik Wikström | |
| | Posted: Mon Aug 18, 2008 8:55 pm Post subject: Re: How to stl library efficiently? | |
| | | |
On 2008-08-17 20:52, Peng Yu wrote:
| Quote: | On Aug 10, 11:28 am, red floyd <no.spam.h...@example.com> wrote:
Peng Yu wrote:
Hi,
I came across some discussion on that improper usage stl library could
make program performance bad. Some tips are trivial, such as using the
appropriate algorithm, choosing the best data structure (say, vector
vs. list).
I'm wondering whether are less obvious tricks to make stl based
program performance as good as the hard coded C program?
Get Scott Meyer's "Effective STL".
It seems that it is a little bit outdated. For example, it mentioned
auto_ptr, but people usually use boost::shared_ptr. I'm wondering what
are the things that have been changed since the book was written.
|
Nothing, the C++ standard has not been update since then. On the other
hand a number of new libraries have been developed and evolved since
then (such as boost), but none of them are part of the C++ standard.
Work on the next version of the C++ standard is ongoing the new version
(which contains something like boost::shared_ptr, and much more) will
hopefully be out in 2009, but it will take a while longer until
compilers and libraries support the new stuff.
--
Erik Wikström
[ See LINK for info about ]
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