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Re: [SG14] SG14 Aug 12 meeting

From: Michael Wong <fraggamuffin_at_[hidden]>
Date: Wed, 12 Aug 2020 15:33:52 -0400
Thank you all, especially to Staffen for chairing and Ben for taking notes.
So far our experiment of having each domain chair run meetings the past 3
months have been working out very well, having done Games, Embedded, and
Finance. Thank you all.

On Wed, Aug 12, 2020 at 3:25 PM Hubert Tong via SG14 <sg14_at_[hidden]>
wrote:

> On Wed, Aug 12, 2020 at 2:58 PM Ben Craig via SG14 <sg14_at_[hidden]>
> wrote:
>
>> Minutes for today’s meeting…
>>
> Thanks Ben.
>
>
>>
>>
>> Ben Craig: Minutes
>>
>> Staffan Tjernstrom: Chair
>>
>> Michael Wong
>>
>> Arthur O'Dwyer
>>
>> Andrew Lumsdaine
>>
>> Basit Ayantunde
>>
>> Billy Baker
>>
>> connor horman
>>
>> Derek Haines
>>
>> Henry Miller
>>
>> Inbal Levi
>>
>> Maxime Laine
>>
>> Muklek Bokth Choudhury
>>
>> Robert Douglas
>>
>> Ronen Friedman
>>
>> Hubert Tong
>>
>>
>>
>>
>>
>> Wong: Inverted meetings: maybe once every three or four months while
>> coronavirus is going. CppCon now fully online. Kona meeting is in
>> Jeopardy. Bulgaria, is the next most likely F2F.
>>
>>
>>
>> Ben: Pitch I've heard is that 6 months after sports start is when we'll
>> have a new F2F
>>
>>
>>
>> Inbal: Virtual plenary is in the works
>>
>>
>>
>> Staffan: All we know is that we don't know.
>>
>>
>>
>>
>>
>> Wong: Affinity was reviewed in SG1, good to move forward into LEWG. Low
>> level one needs more discussion. Now the paper is talking more about
>> interference patterns. Adjacency locality property work was discussed in
>> an inverted meeting.
>>
>>
>>
>> Staffan: I see us doing what needs to be done to get executors done,
>> maybe these will follow along.
>>
>>
>>
>> Inbal: Technical difficulties with ring buffer meeting yesterday.
>> Gathering the various inputs for ring buffer. May want to move some ring
>> buffer things from ring buffer paper to P1958 and P0260. Need use cases.
>> Jens suggested that this be a ring span.
>>
>>
>>
>> From Maxime Lainé to Everyone: 01:22 PM
>>
>> sure, but I can't see any more use cases as those already there sadly..
>> (perhaps something driver related for networking but seems a bit stretched
>> out)
>>
>>
>>
>> From Inbal Levi to Everyone: 01:25 PM
>>
>> Jens have suggested something along the lines of ring_span, so that's one
>> direction. But we need to figure out if Guy's popping-strategy (from P0059)
>> is something that is worth importing to P1958
>>
>>
>>
>> Staffan: LEWGI wasn't thrilled with P1958 interface, but didn't hate it
>> either. LEWGI wanted to see how things differed with ring buffer.
>>
>>
>>
>> Staffan: P0593 implicit object creation. Adopted in the core language as
>> a DR. start_lifetime_as isn't in the library yet. Very confident that it
>> will be in C++23.
>>
>>
>>
>> Staffan: P0593 is important to finance because of pipeline applications,
>> similar to niall's load / unload objects out of memory ideas.
>>
>>
>>
>> Hubert: std::launder won't help with the serialization things.
>>
> I think this needs:
> "in strict terms without ensuring that the lifetime of an appropriate
> object has started".
>
>
>> start_lifetime_as only lets you claim that there is an object, previous
>> references need to go through std::launder.
>>
>>
>>
>> Staffan: Probably wait to talk about member layout control until Rene is
>> able to make it on.
>>
>>
>>
>> Wong: September is probably the right time to reconnect with Renwick to
>> get forward progress on the paper and implementation.
>>
>>
>>
>> Inbal: Trying to summarize decisions that are made in the low cost
>> exception space for a cppcon talk.
>>
>>
>>
>> Ben: Paper in the works to discuss error handling tradeoffs. Will send
>> it to Wong and Inbal.
>>
>>
>>
>> Staffan: Big finance concern is just getting C++20 implemented and seeing
>> the impact, like with jthread and the sync primitives. Seeing real at-scale
>> impact with concepts and modules.
>>
>>
>>
>> Wong: How well does the networking proposal work for finance? Maybe
>> there's an RPC proposal?
>>
>>
>>
>> Staffan: Anything that helps low level timing stability or development
>> throughput is of interest. In finance, lots of people have the same idea
>> at about the same time, but only the first 50% of people or so will make
>> money on it.
>>
>>
>>
>> Wong: How do contracts feel in your space?
>>
>>
>>
>> Staffan: Vital, just not that everyone has realized that what they are
>> doing is contracts work.
>>
>>
>>
>> Wong: Bloomberg is largely doing it for verification.
>>
>>
>>
>> From Robert Douglas to Everyone: 01:46 PM
>>
>> Are there any papers in flight, that anyone is aware of, for attributes
>> for hot/cold, a-la likely/unlikely?
>>
>>
>>
>> Robert Douglas: gnu has hot / cold as well. Has anyone seen a paper
>> along those lines?
>>
>>
>>
>> Staffan: likely / unlikely don't strictly do that, it does help. Not for
>> data though.
>>
>>
>>
>> Staffan: finance ends up living in a weird world where the most common
>> things need to be marked "unlikely" for performance.
>>
>>
>>
>> From Me to Everyone: 01:50 PM
>>
>> Timur Doumler is also trying to drag an assume attribute back from
>> contracts
>>
>>
>>
>> From connor horman to Everyone: 01:52 PM
>>
>> I'd be interested in seeing that as well.
>>
>>
>>
>> Robert Douglas: I usually see this for error handling functions that are
>> marked both as unlikely and cold.
>>
>>
>>
>> Wong: Could use a paper exploring this.
>>
>>
>>
>> From Inbal Levi to Everyone: 01:53 PM
>>
>> Yes. But to my humble understanding, the support is vague.
>>
>>
>>
>> From Maxime Lainé to Everyone: 01:53 PM
>>
>> hot/cold pragmas/markers seems a bit out of language, more of a compiler
>> feature, but I'm open for discussion as well
>>
>>
>>
>> From Inbal Levi to Everyone: 01:53 PM
>>
>> P1774R3
>>
>>
>>
>> Staffan: Would like to have an offline discussion talking about hot /
>> cold.
>>
>>
>>
>> Actions:
>>
>> * Wong to talk with Renwick
>>
>> * Staffan + Robert to talk about object layout
>>
>> * Revisit object layout space when Rene is on the call
>>
>>
>>
>> *From:* SG14 <sg14-bounces_at_[hidden]> *On Behalf Of *Matthew
>> Butler via SG14
>> *Sent:* Wednesday, August 12, 2020 10:14 AM
>> *To:* Low Latency:Game Dev/Financial/Trading/Simulation/Embedded Devices
>> <sg14_at_[hidden]>
>> *Cc:* Matthew Butler <mbutler_at_[hidden]>
>> *Subject:* [EXTERNAL] Re: [SG14] SG14 Aug 12 meeting
>>
>>
>>
>> Me as well.
>>
>>
>>
>> On Wed, Aug 12, 2020 at 9:10 AM René Ferdinand Rivera Morell via SG14 <
>> sg14_at_[hidden]> wrote:
>>
>> Same for me.
>>
>> On Wed, Aug 12, 2020, 11:07 AM Guy Cpp via SG14 <sg14_at_[hidden]>
>> wrote:
>>
>> Apologies: I won't be able to attend this month's meeting. Have a great
>> time!
>>
>>
>>
>> Cheers,
>> G
>>
>>
>>
>> On Tue, 11 Aug 2020 at 17:06, Tjernstrom, Staffan via SG14 <
>> sg14_at_[hidden]> wrote:
>>
>> Topic: SG14 Low Latency Monthly
>>
>> This meeting is Finance focused and is chaired by Staffan Tjernström.
>>
>> Hi,
>>
>> Michael Wong is inviting you to a scheduled Zoom meeting.
>>
>> Topic: SG14 monthly Apr 2020-Oct 2020
>>
>> Time: Jun 11, 2020 02:00 AM Eastern Time (US and Canada) 6 UTC
>> Jun 11, 2020 02:00 AM 6UTC
>> Jul 8, 2020 02:00 PM 18 UTC
>> Aug 12, 2020 02:00 PM 18 UTC
>> Sep 9, 2020 02:00 PM 18 UTC
>> Oct 7, 2020 02:00 PM 18 UTC
>>
>> Join from PC, Mac, Linux, iOS or Android:
>>
>> Password: 013549
>>
>> Or iPhone one-tap :
>> US: +13462487799,,819108882# or +14086380968,,819108882#
>> Or Telephone:
>> Dial(for higher quality, dial a number based on your current
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>> or 877 853 5247 (Toll Free)
>> Meeting ID: 819 108 882
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>> International numbers available: https://iso.zoom.us/u/abhaIjFKLZ
>> <https://urldefense.com/v3/__https:/iso.zoom.us/u/abhaIjFKLZ__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacLmXh7zK$>
>>
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>>
>> Agenda:
>>
>> 1. Opening and introductions
>>
>> 1.1 Roll call of participants
>>
>> 1.2 Adopt agenda
>>
>> 1.3 Approve minutes from previous meeting, and approve publishing
>> previously approved minutes to ISOCPP.org
>>
>> 1.4 Action items from previous meetings
>>
>> 2. Main issues (125 min)
>>
>> 2.1 General logistics
>>
>> Inverted meeting frequency?
>>
>> CPPCON logistics
>> CPPCON Embedded Track: Ben Saks
>> future C++ Standard meetings:
>>
>> 2.2 Paper reviews
>>
>> 2.2.1 any other proposal for reviews?
>>
>> SG14/SG19 features/issues/defects:
>>
>>
>> https://docs.google.com/spreadsheets/d/1JnUJBO72QVURttkKr7gn0_WjP--P0vAne8JBfzbRiy0/edit#gid=0
>> <https://urldefense.com/v3/__https:/docs.google.com/spreadsheets/d/1JnUJBO72QVURttkKr7gn0_WjP--P0vAne8JBfzbRiy0/edit*gid=0__;Iw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacAwLxEYi$>
>>
>> These are more status updates than full-blown reviews this time around.
>>
>> Affinity https://github.com/cplusplus/papers/issues?q=is:issue+P1436
>> <https://urldefense.com/v3/__https:/github.com/cplusplus/papers/issues?q=is:issue*P1436__;Kw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacEOd4ruZ$>
>>
>> System topology discovery
>> https://github.com/cplusplus/papers/issues?q=is:issue+P1795
>> <https://urldefense.com/v3/__https:/github.com/cplusplus/papers/issues?q=is:issue*P1795__;Kw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacG9gxIRs$>
>>
>> Ring Buffer https://github.com/cplusplus/papers/issues?q=is:issue+P0059
>> <https://urldefense.com/v3/__https:/github.com/cplusplus/papers/issues?q=is:issue*P0059__;Kw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacAETJvyX$>
>>
>> Object Creation
>> https://github.com/cplusplus/papers/issues?q=is:issue+P0593
>> <https://urldefense.com/v3/__https:/github.com/cplusplus/papers/issues?q=is:issue*P0593__;Kw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacM7wUnzd$>
>>
>> Member layout control
>> https://github.com/cplusplus/papers/issues?q=is:issue+P1605
>> <https://urldefense.com/v3/__https:/github.com/cplusplus/papers/issues?q=is:issue*P1605__;Kw!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacFPftyFn$>
>>
>> Discuss future direction of detreministic C++ exception group :
>>
>> Low-cost Deterministic C++ Exceptions for Embedded Systems
>> <
>>
>> https://www.research.ed.ac.uk/portal/files/78829292/low_cost_deterministic_C_exceptions_for_embedded_systems.pdf
>> <https://urldefense.com/v3/__https:/www.research.ed.ac.uk/portal/files/78829292/low_cost_deterministic_C_exceptions_for_embedded_systems.pdf__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacHGnA89n$>>
>>
>>
>> Low-cost
>> Deterministic C++ Exceptions for Embedded Systems James Renwick James
>> Renwick et al.
>>
>> 2.3 Domain-specific discussions
>>
>> 2.3.1 SIG chairs
>>
>> - Embedded Programming chairs: Ben Craig, Wouter van Ooijen and Odin
>> Holmes, John McFarlane
>>
>> - Financial/Trading chairs: Staffan Tjernström, Carl Cooke, Neal
>> Horlock,
>> Mateusz Pusz, Clay Trychta,
>> - Games chairs: Rene Riviera, Guy Davidson and Paul Hampson
>> - Linear Algebra chairs: Bob Steagall, Mark Hoemmen, Guy Davidson
>>
>> 2.4 Other Papers and proposals
>>
>> 2.5 Future F2F meetings:
>>
>> 2.6 future C++ Standard meetings:
>> https://isocpp.org/std/meetings-and-participation/upcoming-meetings
>> <https://urldefense.com/v3/__https:/isocpp.org/std/meetings-and-participation/upcoming-meetings__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacH7nNQQe$>
>>
>> - 2020-11: (New York, tentative) Cancelled.
>> - 2021-02-22 to 27: Kona, HI, USA
>>
>> 3. Any other business
>> Reflector
>> https://lists.isocpp.org/mailman/listinfo.cgi/sg14
>> <https://urldefense.com/v3/__https:/lists.isocpp.org/mailman/listinfo.cgi/sg14__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacAJ8MqKp$>
>> As well as look through papers marked "SG14" in recent standards
>> committee
>> paper mailings:
>> http://open-std.org/jtc1/sc22/wg21/docs/papers/2015/
>> <https://urldefense.com/v3/__http:/open-std.org/jtc1/sc22/wg21/docs/papers/2015/__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacK1x_akR$>
>> http://open-std.org/jtc1/sc22/wg21/docs/papers/2016/
>> <https://urldefense.com/v3/__http:/open-std.org/jtc1/sc22/wg21/docs/papers/2016/__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacGaC9T9_$>
>>
>> Code and proposal Staging area
>> https://github.com/WG21-SG14/SG14
>> <https://urldefense.com/v3/__https:/github.com/WG21-SG14/SG14__;!!FbZ0ZwI3Qg!-Cx7ecFH_AJfg5_2VUHA4q_4m6HrgQCiCUI56OFLF7QJGeMDjmTacJ4nXJap$>
>> 4. Review
>>
>> 4.1 Review and approve resolutions and issues [e.g., changes to SG's
>> working draft]
>>
>> 4.2 Review action items (5 min)
>>
>> 5. Closing process
>>
>> 5.1 Establish next agenda
>>
>> 5.2 Future meeting
>>
>> Time: Sep 9, 2020 02:00 PM Eastern Time (US and Canada) : Security:
>> Mathew
>> Butler
>>
>> Time: Oct 14, 2020 02:00 PM Eastern Time (US and Canada): Games: Rene
>>
>>
>>
>>
>>
>> Kind Rgds
>>
>> Staffan Tj.
>>
>> pp Michael Wong
>>
>>
>>
>>
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Received on 2020-08-12 14:37:27