220 34898 article Path: news.gmane.org!.POSTED!not-for-mail From: inkwizytoryankes@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Thoughts on more methods towards containers in the future Date: Sat, 14 Oct 2017 06:49:13 -0700 (PDT) Lines: 147 Approved: news@gmane.org Message-ID: References: <973f04da-1354-44f4-9d1f-23f04596b8dc@isocpp.org> <20171014085305.GA24512@fukushima.lysator.liu.se> <79c51b8c-6cc2-4872-8651-9dae513d1e21@isocpp.org> <1550fc17-cf97-438d-9e7a-862f729adbf5@isocpp.org> <0cc942cf-a217-4175-98b0-b466ac224dc7@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1275_2037593031.1507988954008" X-Trace: blaine.gmane.org 1507988959 14477 195.159.176.226 (14 Oct 2017 13:49:19 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 14 Oct 2017 13:49:19 +0000 (UTC) Cc: euloanty@live.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDDLTAGNTIBBBWVLRDHQKGQEIKG4YBQ@isocpp.org Sat Oct 14 15:49:14 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f69.google.com ([209.85.213.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e3MoO-0002c5-DQ for gclcip-std-proposals@m.gmane.org; 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Sat, 14 Oct 2017 06:49:15 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.159.36.173 with SMTP id 42ls2368862uar.17.gmail; Sat, 14 Oct 2017 06:49:14 -0700 (PDT) X-Received: by 10.31.211.195 with SMTP id k186mr290676vkg.9.1507988954460; Sat, 14 Oct 2017 06:49:14 -0700 (PDT) In-Reply-To: X-Original-Sender: inkwizytoryankes@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:34898 Archived-At: ------=_Part_1275_2037593031.1507988954008 Content-Type: multipart/alternative; boundary="----=_Part_1276_848129416.1507988954009" ------=_Part_1276_848129416.1507988954009 Content-Type: text/plain; charset="UTF-8" On Saturday, October 14, 2017 at 3:27:44 PM UTC+2, ejsvifq mabmip wrote: > > https://github.com/euloanty/cqwrteur-vector/blob/master/deque.cc > > Try this code. > > BTW. deque is "slower" than vector because of this dumb check if > > On Saturday, October 14, 2017 at 9:24:37 AM UTC-4, eulo...@live.com wrote: > >> O2 wont eliminate this cost. It is not optimization issue. I always use >> -O2 to compile my programs >> >> On Saturday, October 14, 2017 at 9:18:56 AM UTC-4, Todd Fleming wrote: >>> >>> On Saturday, October 14, 2017 at 8:45:29 AM UTC-4, ejsvifq mabmip wrote: >>>> >>>> On Saturday, October 14, 2017 at 4:53:10 AM UTC-4, Magnus Fromreide >>>> wrote: >>>>> >>>>> On Fri, Oct 13, 2017 at 07:38:20PM -0700, eulo...@live.com wrote: >>>>> > Contiguous Containers: >>>>> > >>>>> > vector: >>>>> > add non check push_back. non check resize etc. >>>>> >>>>> What does this mean, you are a bit thin on details here. >>>>> >>>>> ok. when you push_back an element into the vector, it will first check >>>> whether size()==capacity(). It is an overhead when you know what exactly >>>> the size of elements you need. >>>> >>>> For example: >>>> >>>> vector v; >>>> v.reserve(10000000); >>>> for(std::size_t i(0);I!=v.capacity();++i) >>>> v.emplace_back(i); >>>> >>>> will be slower than >>>> >>>> vector v; >>>> v.reserve(10000000); >>>> for(std::size_t i(0);I!=v.capacity();++i) >>>> v.nonchecked_emplace_back(i); >>>> >>> >>> Benchmark requested using -O2 or higher; I doubt your performance claim. >>> >>> Todd >>> >>> IMHO if check in `emplace_back` cost is too much for you, you probably create your own container of use some specialized one from SG14. Vector cover 99% use cases, you are probably in 1% that is not included. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/e5065ef4-4802-4241-8357-cfb93ba25bae%40isocpp.org. ------=_Part_1276_848129416.1507988954009 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Saturday, October 14, 2017 at 3:27:44 PM UTC+2,= ejsvifq mabmip wrote:
Try this code.

BTW. deque is &quo= t;slower" than vector because of this dumb check if

On Saturday= , October 14, 2017 at 9:24:37 AM UTC-4, eulo...@live.com wrote:
O2 wont eliminate= this cost. It is not optimization issue. I always use -O2 to compile my pr= ograms

On Saturday, October 14, 2017 at 9:18:56 AM UTC-4, Todd Flemi= ng wrote:
On Saturd= ay, October 14, 2017 at 8:45:29 AM UTC-4, ejsvifq mabmip wrote:
On Saturday, October 14, 2017 = at 4:53:10 AM UTC-4, Magnus Fromreide wrote:
On Fri, Oct 13, 2017 at 07:38:20PM -0700, eulo= ....@live.com wrote:
> Contiguous Containers:
>=20
> vector:
> add non check push_back. non check resize etc.

What does this mean, you are a bit thin on details here.

ok. when you push_back an element into the vector, it= will first check whether size()=3D=3Dcapacity(). It is an overhead when yo= u know what exactly the size of elements you need.

For example:

vector<std::size_t> v;
v.reserve(10000000);
for(std::size_t i(0);I!=3Dv.capacity(= );++i)
=C2=A0 =C2=A0=C2=A0 v.emplace_back(i);

will be slower than

vector<std::size= _t> v;
v.reserve(10000000);
for(std::= size_t i(0);I!=3Dv.capacity();++i)
=C2=A0 =C2=A0=C2=A0 v.noncheck= ed_emplace_back(i);

Bench= mark requested using -O2 or higher; I doubt your performance claim.

Todd

=C2=A0
IMHO if check in `emplace_ba= ck` cost is too much for you, you probably create your own container of use= some specialized one from SG14.
Vector cover 99% use cases, you = are probably in 1% that is not included.

--
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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/e5065ef4-4802-4241-8357-cfb93ba25bae= %40isocpp.org.
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