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Groups > comp.programming.threads > #1805
| From | Anthony Williams <anthony.ajw@gmail.com> |
|---|---|
| Newsgroups | comp.programming.threads |
| Subject | Re: forcing the compiler to reload from memory with c++0x |
| References | (4 earlier) <69d82db7-34be-4de7-86c4-2f39cc1e6df3@m13g2000yqb.googlegroups.com> <4d4221e9$0$17247$426a74cc@news.free.fr> <6de164c4-4e91-4c94-a8c8-240349de9cd2@x18g2000yqe.googlegroups.com> <4d45e2d2$0$27524$426a74cc@news.free.fr> <ee1296a2-2a54-42c2-b37c-5c9cf270ea4a@d23g2000prj.googlegroups.com> |
| Date | 2011-02-01 23:33 +0000 |
| Message-ID | <87fws7wcrw.fsf@justsoftwaresolutions.co.uk> (permalink) |
| Organization | CNNTP |
Joshua Maurice <joshuamaurice@gmail.com> writes: > On Jan 30, 2:14 pm, David Jobet <david.jo...@free.fr> wrote: >> If it applies, then it means that an atomic load relaxed implies : >> - no ordering guarantee (that one everybody agrees) > > Actually, I don't think that I agree. > > I admit I'm not the best on this, but it's my understanding that each > atomic variable has a modification order, and no reads can read values > in an order which is inconsistent with this modification order. Is > this right? Ex: > > //all loads and stores are std::memory_order_relaxed > //start up the two threads simultaneously > > //initial condition > x = 0; > > //thread 1 > x = 1; > x = 2; > x = 3; > x = 4; > > //thread 2 > cout << x << endl; > cout << x << endl; > cout << x << endl; > cout << x << endl; > > It's my understanding that the program may not print the following. Is > that correct? > 1 > 3 > 2 > 4 Yes, that is correct. Anthony -- Author of C++ Concurrency in Action http://www.stdthread.co.uk/book/ just::thread C++0x thread library http://www.stdthread.co.uk Just Software Solutions Ltd http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976
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Re: forcing the compiler to reload from memory with c++0x David Jobet <david.jobet@free.fr> - 2011-01-30 17:14 -0500 Re: forcing the compiler to reload from memory with c++0x Anthony Williams <anthony.ajw@gmail.com> - 2011-02-01 23:33 +0000 Re: forcing the compiler to reload from memory with c++0x Joshua Maurice <joshuamaurice@gmail.com> - 2011-02-01 15:12 -0800 Re: forcing the compiler to reload from memory with c++0x Dmitriy Vyukov <dvyukov@gmail.com> - 2011-01-31 01:07 -0800
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