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From: "thiago at kde dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/99277] New: C++2a synchronisation is inefficient in GCC 11 and can't be fixed later Date: Thu, 25 Feb 2021 23:27:53 +0000 [thread overview] Message-ID: <bug-99277-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99277 Bug ID: 99277 Summary: C++2a synchronisation is inefficient in GCC 11 and can't be fixed later Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: thiago at kde dot org Target Milestone: --- Requesting that this be treated as a blocker for GCC 11. Detailed post: https://gcc.gnu.org/pipermail/libstdc++/2021-February/052043.html Summary: Since everything in this implementation is inline and, once released, it will tie our hands until the next ABI break (libstdc++.so.7). And no, inline namespaces and ABI tags are no different than ABI breaks, they only make the ABI break more or less silent in the process. Here's a summary of the findings: 1) everything is inline 2) futex code is still behind a lot of code calling into std::_Hash_bytes 3) other int-sized (incl. enums) atomics don't use futex 4) std::latch and std::counting_semaphore defaults preclude from using futex on Linux 5) std::barrier implementation also uses a type that futex(2) can't handle
next reply other threads:[~2021-02-25 23:27 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-25 23:27 thiago at kde dot org [this message] 2021-02-26 0:05 ` [Bug libstdc++/99277] " hjl.tools at gmail dot com 2021-02-26 7:22 ` [Bug libstdc++/99277] [11 Regression] " rguenth at gcc dot gnu.org 2021-02-26 12:18 ` jakub at gcc dot gnu.org 2021-02-26 12:52 ` [Bug libstdc++/99277] " redi at gcc dot gnu.org 2021-02-26 19:14 ` [Bug libstdc++/99277] C++2a synchronisation is inefficient in GCC 11 thiago at kde dot org 2021-02-27 2:22 ` ville.voutilainen at gmail dot com 2021-02-27 3:21 ` thiago at kde dot org 2021-04-27 11:40 ` jakub at gcc dot gnu.org 2021-04-27 14:38 ` thiago at kde dot org 2021-04-27 15:40 ` redi at gcc dot gnu.org 2022-05-06 8:30 ` jakub at gcc dot gnu.org 2023-05-08 12:21 ` rguenth at gcc dot gnu.org 2023-05-08 15:15 ` thiago at kde dot org 2023-05-08 16:39 ` redi at gcc dot gnu.org 2023-05-08 18:52 ` thiago at kde dot org 2023-05-08 19:16 ` rodgertq at gcc dot gnu.org 2023-05-08 19:42 ` thiago at kde dot org 2023-05-08 20:00 ` redi at gcc dot gnu.org 2023-05-08 20:28 ` thiago at kde dot org 2023-05-08 20:52 ` redi at gcc dot gnu.org 2023-05-08 20:55 ` thiago at kde dot org 2023-05-08 21:16 ` redi at gcc dot gnu.org 2023-05-08 23:06 ` rodgertq at gcc dot gnu.org
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