220 14199 <572122be-61c5-4b25-aef6-fee76dcd13da@isocpp.org> article Path: news.gmane.org!not-for-mail From: Gor Nishanov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: comment on n4244 Date: Fri, 24 Oct 2014 08:48:40 -0700 (PDT) Lines: 89 Approved: news@gmane.org Message-ID: <572122be-61c5-4b25-aef6-fee76dcd13da@isocpp.org> References: <5d78c59b-4d67-45f6-9d99-8c4beeeac055@isocpp.org> <5344687e-e1de-4205-885c-b5c2f9580129@isocpp.org> <187da710-8adc-4516-bf64-263951503bc7@isocpp.org> <42ddf641-27c7-42a5-ab1c-772667797e5b@isocpp.org> <05a08ac6-f9b8-4ebb-9cb8-9a37a6fd4527@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_1381_183351237.1414165720752" X-Trace: ger.gmane.org 1414165731 10091 80.91.229.3 (24 Oct 2014 15:48:51 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 24 Oct 2014 15:48:51 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC47RF4IW4GRBWXJVGRAKGQEH4K3FRA@isocpp.org Fri Oct 24 17:48:44 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qc0-f200.google.com ([209.85.216.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xhh6a-0000M7-0W for gclcip-std-proposals@m.gmane.org; Fri, 24 Oct 2014 17:48:44 +0200 Original-Received: by mail-qc0-f200.google.com with SMTP id r5sf3152713qcx.3 for ; Fri, 24 Oct 2014 08:48:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=pwcwZzFlRxnMODpMQJVCdqytFfSJGxp2xHBm5i+L3AE=; b=JjmV0tBcQ+ze8KUn55lASf+9ynvnLYSqo7Q4eOGA9VPNXOVo0y/CHZd20gE7eIo7MV xHoTUbRfhiPS7WJBc4jlxgyIciFpQlcSmp9hBFvifU1u3WCjxazzwmsCsYX2RFSFNNkD 6Q6jllynBvADFguhgV36PaHI6RUsQjKVTEObZlP0qwXle0DWeoLNbTJ6RXy1sEzZnNXO oUKOz/LIXDxTY4AuFnW+8ykdRUQWxIOS1k4JDzB8CpiCVd3icLpDZYqGmSScfr2d5wCz 9EYDTIolUwLNTr829w2XGaWMcPYm/iH8c6aarifpkW6iG54KvqsB/OD2s/4db5ZxxZkB J6HQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=pwcwZzFlRxnMODpMQJVCdqytFfSJGxp2xHBm5i+L3AE=; b=H9Cp2urP+mUyrhtHK/Q7On6/IqZPiTraoqGNzXBzQAjEh2LVzJLGvmd7Z+RQ4k934N +3dDB84k9zBLQLSgmqnxosyXt/d0wZcbLr+osa8GZu5silZdUUXkX9jdigtqp4PeNwvJ Jw3/XpgW3Guf2OwOl8U7PpAFpLFRqrS/ypKmrsa8PXjdLBdQNIl/4qDMzvkMwuxaxPbO AAXNFwViuAETgPY56t07nzpcfhMglTjO9PVaBc/sMW69wxD4ASzJAlur8HeIxqtGjxDh HqOVYV6UiSIbp8MOMuhE9sLB5kc93fX9a51hlj7weK84QjR/uYrm3BGQ7w3+OqyDgZ+Y 6gSg== X-Gm-Message-State: ALoCoQksKtx3E1wdcEmoR88fuu+cBoz22L3ti/tW7qsrcnmikAQGU8msv5GtCeLMLAzM4MIxYmon X-Received: by 10.224.122.15 with SMTP id j15mr8094182qar.6.1414165722841; Fri, 24 Oct 2014 08:48:42 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.2.7 with SMTP id 7ls211165igq.5.gmail; Fri, 24 Oct 2014 08:48:42 -0700 (PDT) X-Received: by 10.50.138.40 with SMTP id qn8mr58897igb.2.1414165722074; Fri, 24 Oct 2014 08:48:42 -0700 (PDT) In-Reply-To: X-Original-Sender: GorNishanov@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:14199 Archived-At: ------=_Part_1381_183351237.1414165720752 Content-Type: text/plain; charset=UTF-8 On Friday, October 24, 2014 7:51:38 AM UTC-7, Oliver Kowalke wrote: > > 2014-10-24 16:46 GMT+02:00 Giovanni Piero Deretta >: > >> hum, 41ns per iteration seems a bit high. A stackful coroutine yield >> should be around 10 clock cycles: save callee save registers, restore >> callee save registers (saving and restoring can be done in parallel), pop >> return address and jump (perfectly predictable in this case). >> > > it depends on the architecture (compare x86_64 SYSV and x86_64 Win64). > maybe Gor missed to enabled optimization and/or to spec. > BOOST_DISABLE_ASSERTS > This is x86_64 win64. I did not specify as you see in the snippet, I used default attributes (that save floats). Adding attributes(flag_fpu_t::fpu_not_preserved) drops it down from: Stackful: 0.417057 secs: yields 10000000 values 41.705700ns per eac to recurse completes in 0.360136 secs: yields 10000001 values 36.013576ns per each Though I consider that with modern compilers and CPU not saving floats is dangerous, unless you disable loop vectorization. -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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On Friday, October 24, 2014 7:51:38 AM UTC-7, Oli= ver Kowalke wrote:
2014-10-24 16:46 GMT+02:00 Giovanni Pi= ero Deretta <gpde= ....@gmail.com>:
hum, 41ns per iteration seems a bit high. A stackfu= l coroutine yield should be around 10 clock cycles: save callee save regist= ers, restore callee save registers (saving and restoring can be done in par= allel), pop return address and jump (perfectly predictable in this case).

it depends on the architect= ure (compare x86_64 SYSV and x86_64 Win64).
maybe Gor missed = to enabled optimization and/or to spec. BOOST_DISABLE_ASSERTS

This is x86_64 win64. I did not specify = as you see in the snippet, I used default attributes (that save floats). Ad= ding attributes(flag_fpu_t::fpu_not_preserved) drops it down from:

Stackful:&= nbsp;0.417057 secs: yields 10000000 values 41.705700ns per eac
to
rec= urse completes in 0.360136 secs: yields 10000001 values 36.013576ns per eac= h
 
Though I consider that with modern compi= lers and CPU not saving floats is dangerous, unless you disable loop vector= ization.

--

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