Re: Consequential RCU

From	Joseph Seigh <jseigh_es00@xemaps.com>
Newsgroups	comp.lang.c++
Subject	Re: Consequential RCU
Date	2026-10-02 14:39 -0400
Organization	A noiseless patient Spider
Message-ID	<119otp7$2bs8n$1@dont-email.me> (permalink)
References	(5 earlier) <119486r$33haq$1@dont-email.me> <11954k8$3b7ne$1@dont-email.me> <119eqg6$2p6s6$1@dont-email.me> <119fmgv$316ju$2@dont-email.me> <119hhni$3oib4$1@dont-email.me>

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On 9/29/26 7:30 PM, Chris M. Thomasson wrote:
> On 9/28/2026 11:40 PM, David Brown wrote:
>> On 29/09/2026 00:42, Chris M. Thomasson wrote:
...
>>
>> (Of course for this particular case, if you can persuade the gcc C++ 
>> library folk to make their standard cas16 lock-free, then using the 
>> standard function is best.)
> Difficult to totally disagree with that David. Shit. Its my own personal 
> problem with the syntax of GCC inline asm. I am a bit scared of it. 
> Sigh. Clobbers what? When and where? cdecl for the ABI and externally 
> assembled functions are fine for me, LTO aside for a moment, can be bad 
> do not go into my asm! BUT. Again. Shit. Its a personal problem wrt me 
> saying inline bad! Sorry!
> 
> Also, if C++ gains a LOCK CMPXCHG16B for a double word, two contiguous 
> 64 bit words on a 64 bit machine, well GOOD! Show me. I have had some 
> experiences with it trying to tell me its not lock free.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80878

The rationale seems to be you can mix a lock-free operation
with locked operations since __atomic_always_lock_free and
__atomic_is_lock_free apply to the data type not specific
builtins.

Given that there seems to be no shortage of x86 specific
gcc builtins, I can't think of any reason why there's
no cmpxchg16b builtin.

Thread

Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-16 18:25 -0400
  Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-18 16:07 -0400
  Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-19 13:34 -0700
    Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-20 10:58 -0400
      Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-20 14:51 -0700
      Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-20 16:09 -0700
        Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-20 20:19 -0400
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-20 19:26 -0700
        Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-21 14:50 +0200
          Re: Consequential RCU boltar@caprica.universe - 2026-09-21 15:47 +0000
            Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-21 18:45 +0200
              Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-09-25 18:25 +0200
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-25 18:40 +0200
                Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-25 13:47 -0400
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-25 20:54 +0200
                Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-25 17:20 -0400
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-26 16:23 +0200
                Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-09-26 15:36 -0400
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-27 14:56 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-28 15:50 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-29 08:31 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-02 11:13 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-03 14:19 +0200
                Re: Consequential RCU boltar@caprica.universe - 2026-10-03 15:50 +0000
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-03 14:12 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-04 11:34 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 17:13 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-09 08:33 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-12 12:58 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 17:15 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-28 15:44 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-28 15:45 -0700
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-24 15:31 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-24 15:28 -0700
            Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-25 08:33 +0200
              Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-28 15:42 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-29 08:40 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-29 16:30 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-09-30 09:54 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-02 11:11 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-03 14:22 +0200
                Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-02 14:39 -0400
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 11:39 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-06 06:28 +0200
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-06 08:36 +0200
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-06 10:38 +0200
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-06 10:42 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 13:19 -0700
                Re: Consequential RCU David Brown <david.brown@hesbynett.no> - 2026-10-07 10:49 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-07 13:11 -0700
  Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-05 19:00 +0200
    Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-05 10:57 -0700
      Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-05 21:03 +0200
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 13:15 -0700
          Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-07 05:19 +0200
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 21:29 -0700
              Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-07 15:01 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-07 13:12 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-08 05:57 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 11:41 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-09 08:16 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-19 12:07 -0700
      Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-05 21:23 +0200
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 13:18 -0700
          Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-07 05:19 +0200
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 18:10 -0700
              Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-09 08:16 +0200
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 21:31 -0700
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 21:33 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-06 21:34 -0700
          Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-07 15:00 +0200
            Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-07 15:26 +0200
              Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-07 13:17 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-08 05:55 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 12:19 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 14:20 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-09 08:14 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-09 11:05 -0700
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-07 13:13 -0700
              Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-08 05:56 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-10 14:20 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-11 06:59 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 14:07 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-12 05:18 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 20:31 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-12 06:32 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-12 13:14 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-13 08:14 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 00:08 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 00:10 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-13 09:43 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 12:29 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-14 05:56 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-14 14:02 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-16 05:28 +0200
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-16 13:28 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-12 13:19 -0700
                Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-12 13:24 -0700
                Re: Consequential RCU Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-13 11:33 +0200
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 18:53 -0700
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-08 18:55 -0700
  Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-11 11:11 -0400
    Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 14:10 -0700
      Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-11 21:44 -0400
        Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 20:04 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 20:07 -0700
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-11 20:34 -0700
    Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-13 13:01 -0400
      Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 12:36 -0700
        Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-13 19:34 -0400
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 16:46 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-14 14:16 -0700
            Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-14 14:46 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-15 11:23 -0700
          Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-15 11:26 -0700
      Re: Consequential RCU "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-15 11:49 -0700
        Re: Consequential RCU Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-15 19:26 -0400

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