Hardware Transactional Memory, the end?

By: --- (---.delete@this.redheron.com), August 23, 2022 10:00 am
Room: Moderated Discussions
Andrey (andrey.semashev.delete@this.gmail.com) on August 23, 2022 6:29 am wrote:
> --- (---.delete@this.redheron.com) on August 21, 2022 9:27 pm wrote:
> > Andrey (andrey.semashev.delete@this.gmail.com) on August 21, 2022 6:39 pm wrote:
> > >
> > > The key advantage of transactional memory is atomicity of *multiple* memory accesses,
> > > at potentially distant memory locations. No predictor will give you that.
> >
> > I'm no expert, but this seems to me too strong a claim.
> > I make no claims as to whether it's a good use of transistors, but I could imagine a two
> > level system that starts by detecting patterns of atomics that occur close to each in
> > time, and that that then predicts an overall outcome, all held as speculative in the same
> > way as HTM (ie vie special "don't propagate this" bits in each cache line)...
>
> Architecturally, two atomic operations are distinct and are not atomic in combination. This is regardless
> of whether the particular hardware manages to somehow commit the two operations as one atomic operation.
> Being architecturally atomic is what is important here because that is what software relies on.
>
> HTM, on the other hand, is architectural (i.e. not speculative). That is, the architecture guarantees,
> within set limits, that a certain sequence of operations will execute atomically.


I understand this Andrey, but you apparently did not understand the distinction I was trying to make.
Is what people want from HTM
- PERFORMANCE (which can be achieved, I think, by speculation, as I suggested) OR
- EASIER writing of code (which can be achieved, I think, by language+compiler, with any theoretical performance that's left on the table being made up by speculation).

HTM is a means to an end, it's not an end in itself. But is that end
- performance OR
- making it easier to write reliable parallel code
?
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TopicPosted ByDate
Hardware Transactional Memory, the end?rwessel2022/08/20 06:50 PM
  Hardware Transactional Memory, the end?Kara2022/08/20 11:04 PM
    Hardware Transactional Memory, the end?dmcq2022/08/21 11:36 AM
      Hardware Transactional Memory, the end?rwessel2022/08/21 12:17 PM
        Hardware Transactional Memory, the end?---2022/08/21 01:26 PM
          Hardware Transactional Memory, the end?Andrey2022/08/21 06:39 PM
            Hardware Transactional Memory, the end?---2022/08/21 09:27 PM
              Hardware Transactional Memory, the end?Andrey2022/08/23 06:29 AM
                Hardware Transactional Memory, the end?---2022/08/23 10:00 AM
                  Hardware Transactional Memory, the end?iz2022/08/23 01:20 PM
                    Hardware Transactional Memory, the end?anonymou52022/08/23 02:57 PM
                  Hardware Transactional Memory, the end?Andrey2022/08/23 06:01 PM
                    Hardware Transactional Memory, the end?Anon2022/08/23 06:28 PM
                      Hardware Transactional Memory, the end?Andrey2022/08/24 04:10 AM
                        Hardware Transactional Memory, the end?Anon2022/08/24 08:50 AM
                          Hardware Transactional Memory, the end?rwessel2022/08/24 09:35 AM
                          Hardware Transactional Memory, the end?Etienne2022/08/25 01:54 AM
                            Hardware Transactional Memory, the end?Anon2022/08/25 05:25 AM
                              Hardware Transactional Memory, the end?Etienne2022/08/25 06:24 AM
                                Hardware Transactional Memory, the end?rwessel2022/08/25 08:16 AM
                                  Hardware Transactional Memory, the end?Linus Torvalds2022/08/25 10:16 AM
                                    Hardware Transactional Memory, the end?rwessel2022/08/25 11:00 AM
                                  Hardware Transactional Memory, the end?Etienne2022/08/26 12:54 PM
                    Hardware Transactional Memory, the end?anon22022/08/23 08:50 PM
                      Hardware Transactional Memory, the end?Andrey2022/08/24 03:54 AM
                        Hardware Transactional Memory, the end?anon22022/08/24 04:54 AM
                      Hardware Transactional Memory, the end?Simon Farnsworth2022/08/24 03:58 AM
                        Hardware Transactional Memory, the end?Konrad Schwarz2022/08/28 06:12 AM
          Hardware Transactional Memory, the end?Linus Torvalds2022/08/21 06:58 PM
            Hardware Transactional Memory, the end?rwessel2022/08/21 08:02 PM
              Hardware Transactional Memory, the end?anon22022/08/21 09:31 PM
                Hardware Transactional Memory, the end?dmcq2022/08/22 07:14 AM
                  Hardware Transactional Memory, the end?anon22022/08/23 12:15 AM
                    Hardware Transactional Memory, the end?dmcq2022/08/24 03:50 AM
                      Hardware Transactional Memory, the end?Linus Torvalds2022/08/24 11:56 AM
                        Hardware Transactional Memory, the end?dmcq2022/08/25 04:39 PM
            Hardware Transactional Memory, the end?---2022/08/21 09:33 PM
              Hardware Transactional Memory, the end?Linus Torvalds2022/08/22 11:32 AM
                Hardware Transactional Memory, the end?Anon2022/08/22 12:35 PM
                  Hardware Transactional Memory, the end?rwessel2022/08/22 04:47 PM
                Hardware Transactional Memory, the end?gpd2022/08/26 03:07 AM
                  Hardware Transactional Memory, the end?Michael S2022/08/26 03:46 AM
                    Hardware Transactional Memory, the end?Linus Torvalds2022/08/26 11:01 AM
                      Hardware Transactional Memory, the end?rwessel2022/08/26 06:08 PM
                        Hardware Transactional Memory, the end?anonymou52022/08/26 07:52 PM
  Hardware Transactional Memory, the end?zArchJon2022/08/24 10:12 AM
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