Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #117942

Re: Why volatile may make sense for parallel code today.

From "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups comp.lang.c++
Subject Re: Why volatile may make sense for parallel code today.
Date 2023-11-24 01:05 -0800
Organization A noiseless patient Spider
Message-ID <ujpp19$28srl$2@dont-email.me> (permalink)
References (6 earlier) <ujo3dr$1p192$1@i2pn2.org> <ujpl1a$28aoq$3@raubtier-asyl.eternal-september.org> <ujpm48$28gcu$1@dont-email.me> <ujpmue$28j0j$1@raubtier-asyl.eternal-september.org> <ujpovj$28srl$1@dont-email.me>

Show all headers | View raw

On 11/24/2023 1:04 AM, Chris M. Thomasson wrote:
> On 11/24/2023 12:30 AM, Bonita Montero wrote:
>> Am 24.11.2023 um 09:16 schrieb Chris M. Thomasson:
>>
>>> std::atomic is going to work for such a flag. Depending on your
>>> setup, it should be using std::memory_order_relaxed for the polling.
>>
>> There's also atomic_flag, but it has some limitations over atomic_bool
>> that I've never used it. You can set it only in conjunction with an
>> atomic read and I never had a use for that. And this relies on a atomic
>> exchange, which costs a lot more than just a byte write.
> 
> Fwiw, this flag should be aligned on a l2 cache line boundary, and 
> padded up to a l2 cache line size.

You can stuff a cache line with words, as long as you do not straddle a 
cache line boundary... YIKES!

Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-22 17:35 +0100
  Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-22 13:22 -0800
    Re: Why volatile may make sense for parallel code today. red floyd <no.spam.here@its.invalid> - 2023-11-22 16:17 -0800
      Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-22 21:05 -0800
        Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-22 21:06 -0800
          Re: Why volatile may make sense for parallel code today. Marcel Mueller <news.5.maazl@spamgourmet.org> - 2023-12-01 08:50 +0100
        Re: Why volatile may make sense for parallel code today. David Brown <david.brown@hesbynett.no> - 2023-11-23 10:02 +0100
          Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-23 10:35 +0100
          Re: Why volatile may make sense for parallel code today. scott@slp53.sl.home (Scott Lurndal) - 2023-11-23 19:55 +0000
            Re: Why volatile may make sense for parallel code today. David Brown <david.brown@hesbynett.no> - 2023-11-24 10:08 +0100
        Re: Why volatile may make sense for parallel code today. Richard Damon <richard@damon-family.org> - 2023-11-23 11:07 -0500
          Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-23 17:20 +0100
            Re: Why volatile may make sense for parallel code today. Richard Damon <richard@damon-family.org> - 2023-11-23 12:50 -0500
              Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 08:57 +0100
                Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 00:16 -0800
                Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 09:30 +0100
                Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 01:04 -0800
                Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 01:05 -0800
              Re: Why volatile may make sense for parallel code today. David Brown <david.brown@hesbynett.no> - 2023-11-24 10:23 +0100
            Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 22:05 -0800
              Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 22:53 -0800
              Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 08:53 +0100
                Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 01:06 -0800
                Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 10:10 +0100
            Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 01:14 -0800
              Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 15:32 -0800
    Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-23 08:08 +0100
      Re: Why volatile may make sense for parallel code today. Kaz Kylheku <864-117-4973@kylheku.com> - 2023-11-23 08:26 +0000
        Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-23 09:31 +0100
          Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-23 15:39 +0100
      Re: Why volatile may make sense for parallel code today. scott@slp53.sl.home (Scott Lurndal) - 2023-11-23 19:56 +0000
        Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 05:26 +0100
          Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 21:53 -0800
          Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 21:59 -0800
        Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 21:47 -0800
  Re: Why volatile may make sense for parallel code today. Kaz Kylheku <864-117-4973@kylheku.com> - 2023-11-23 20:32 +0000
    Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-24 05:27 +0100
      Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-23 21:55 -0800
      Re: Why volatile may make sense for parallel code today. David Brown <david.brown@hesbynett.no> - 2023-11-24 10:35 +0100
      Re: Why volatile may make sense for parallel code today. Kaz Kylheku <864-117-4973@kylheku.com> - 2023-11-24 18:27 +0000
        Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-24 15:37 -0800
        Re: Why volatile may make sense for parallel code today. Bonita Montero <Bonita.Montero@gmail.com> - 2023-11-25 13:11 +0100
          Re: Why volatile may make sense for parallel code today. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-11-25 14:46 -0800

csiph-web