By: anon (anon.delete@this.anon.com), August 22, 2018 5:52 pm
Room: Moderated Discussions
Gabriele Svelto (gabriele.svelto.delete@this.gmail.com) on August 22, 2018 3:07 pm wrote:
> anon (anon.delete@this.anon.com) on August 21, 2018 4:27 pm wrote:
> > I assume you mean each core sending a non-cache-coherent message off core somewhere (a memory
> > controller?) which atomically increments a single location. That's crazy. First of all you have
> > the same scaling problem, now you just offloaded it to the non-coherent messaging system and
> > the entity performing the remote atomic. Secondly, high performance use cases that would care
> > (like networking) literally count cache misses (or any type of operation that goes out of the
> > core). Adding one more per packet might cut your performance by double digit percentages.
>
> And yet there have been high-performance network processors implementing those.
Not a very convincing argument. There has been a lot of crap implemented. Transactional memory is a vast, massive complexity to hardware and everyone was warned before they started it that there are better ways to do scalable software, and yet high performance processors still implemented it.
I have no doubt that for a particular case study you can make something go faster if you take your old software and convert it to use remote atomics in some parts. Possibly even some niches like dedicated network processors where the feature does actually make sense.
I was mostly talking about high performance general purpose CPUs, but even in the case of network processor, depending on your exact requirements of the stats, I would not be surprised if stats counting could be kept local most of the time and save more energy and cost than shooting atomics to shared memory/cache all the time.
> anon (anon.delete@this.anon.com) on August 21, 2018 4:27 pm wrote:
> > I assume you mean each core sending a non-cache-coherent message off core somewhere (a memory
> > controller?) which atomically increments a single location. That's crazy. First of all you have
> > the same scaling problem, now you just offloaded it to the non-coherent messaging system and
> > the entity performing the remote atomic. Secondly, high performance use cases that would care
> > (like networking) literally count cache misses (or any type of operation that goes out of the
> > core). Adding one more per packet might cut your performance by double digit percentages.
>
> And yet there have been high-performance network processors implementing those.
Not a very convincing argument. There has been a lot of crap implemented. Transactional memory is a vast, massive complexity to hardware and everyone was warned before they started it that there are better ways to do scalable software, and yet high performance processors still implemented it.
I have no doubt that for a particular case study you can make something go faster if you take your old software and convert it to use remote atomics in some parts. Possibly even some niches like dedicated network processors where the feature does actually make sense.
I was mostly talking about high performance general purpose CPUs, but even in the case of network processor, depending on your exact requirements of the stats, I would not be surprised if stats counting could be kept local most of the time and save more energy and cost than shooting atomics to shared memory/cache all the time.
Topic | Posted By | Date |
---|---|---|
ARM turns to a god and a hero | AM | 2018/08/16 08:32 AM |
ARM turns to a god and a hero | Maynard Handley | 2018/08/16 08:41 AM |
ARM turns to a god and a hero | Doug S | 2018/08/16 10:11 AM |
ARM turns to a god and a hero | Geoff Langdale | 2018/08/16 10:59 PM |
ARM turns to a god and a hero | dmcq | 2018/08/17 04:12 AM |
ARM is somewhat misleading | Adrian | 2018/08/16 10:56 PM |
It's marketing material | Gabriele Svelto | 2018/08/17 12:00 AM |
It's marketing material | Michael S | 2018/08/17 02:13 AM |
It's marketing material | dmcq | 2018/08/17 04:23 AM |
It's marketing material | Andrei Frumusanu | 2018/08/17 06:25 AM |
It's marketing material | Linus Torvalds | 2018/08/17 10:20 AM |
It's marketing material | Groo | 2018/08/17 12:44 PM |
It's marketing material | Doug S | 2018/08/17 01:14 PM |
promises and deliveries | AM | 2018/08/17 01:32 PM |
promises and deliveries | Passing Through | 2018/08/17 02:02 PM |
Just by way of clarification | Passing Through | 2018/08/17 02:15 PM |
Just by way of clarification | AM | 2018/08/18 11:49 AM |
Just by way of clarification | Passing Through | 2018/08/18 12:34 PM |
This ain't the nineties any longer | Passing Through | 2018/08/18 12:54 PM |
This ain't the nineties any longer | Maynard Handley | 2018/08/18 01:50 PM |
This ain't the nineties any longer | Passing Through | 2018/08/18 02:57 PM |
This ain't the nineties any longer | Passing Through | 2018/09/06 01:42 PM |
This ain't the nineties any longer | Maynard Handley | 2018/09/07 03:10 PM |
This ain't the nineties any longer | Passing Through | 2018/09/07 03:48 PM |
This ain't the nineties any longer | Maynard Handley | 2018/09/07 04:22 PM |
Just by way of clarification | Wilco | 2018/08/18 12:26 PM |
Just by way of clarification | Passing Through | 2018/08/18 12:39 PM |
Just by way of clarification | none | 2018/08/18 09:52 PM |
Just by way of clarification | dmcq | 2018/08/19 07:32 AM |
Just by way of clarification | none | 2018/08/19 07:54 AM |
Just by way of clarification | dmcq | 2018/08/19 10:24 AM |
Just by way of clarification | none | 2018/08/19 10:52 AM |
Just by way of clarification | Gabriele Svelto | 2018/08/19 05:41 AM |
Just by way of clarification | Passing Through | 2018/08/19 08:25 AM |
Whiteboards at Gatwick airport anyone? | Passing Through | 2018/08/20 03:24 AM |
It's marketing material | Michael S | 2018/08/18 10:12 AM |
It's marketing material | Brett | 2018/08/18 04:22 PM |
It's marketing material | Brett | 2018/08/18 04:33 PM |
It's marketing material | Adrian | 2018/08/19 12:21 AM |
A76 | AM | 2018/08/17 01:45 PM |
A76 | Michael S | 2018/08/18 10:20 AM |
A76 | AM | 2018/08/18 11:39 AM |
A76 | Michael S | 2018/08/18 11:49 AM |
A76 | AM | 2018/08/18 12:06 PM |
A76 | Doug S | 2018/08/18 12:43 PM |
A76 | Maynard Handley | 2018/08/18 01:42 PM |
A76 | Maynard Handley | 2018/08/18 03:22 PM |
Why write zeros when one can use metadata? | Paul A. Clayton | 2018/08/18 05:19 PM |
Why write zeros when one can use metadata? | Maynard Handley | 2018/08/19 10:12 AM |
Dictionary compress might apply to memcopy | Paul A. Clayton | 2018/08/19 12:45 PM |
Instructions for zeroing | Konrad Schwarz | 2018/08/30 05:37 AM |
Instructions for zeroing | Maynard Handley | 2018/08/30 07:41 AM |
Instructions for zeroing | Adrian | 2018/08/30 10:37 AM |
dcbz -> dcbzl (was: Instructions for zeroing) | hobold | 2018/08/31 12:50 AM |
dcbz -> dcbzl (was: Instructions for zeroing) | dmcq | 2018/09/01 04:28 AM |
A76 | Travis | 2018/08/19 10:36 AM |
A76 | Maynard Handley | 2018/08/19 11:22 AM |
A76 | Travis | 2018/08/19 01:07 PM |
A76 | Maynard Handley | 2018/08/19 05:24 PM |
Remote atomics | matthew | 2018/08/19 11:51 AM |
Remote atomics | Michael S | 2018/08/19 12:58 PM |
Remote atomics | matthew | 2018/08/19 01:32 PM |
Remote atomics | Michael S | 2018/08/19 01:36 PM |
Remote atomics | matthew | 2018/08/19 01:48 PM |
Remote atomics | Michael S | 2018/08/19 02:16 PM |
Remote atomics | Ricardo B | 2018/08/20 09:05 AM |
Remote atomics | dmcq | 2018/08/19 01:33 PM |
Remote atomics | Travis | 2018/08/19 01:32 PM |
Remote atomics | Michael S | 2018/08/19 01:46 PM |
Remote atomics | Travis | 2018/08/19 04:35 PM |
Remote atomics | Michael S | 2018/08/20 02:29 AM |
Remote atomics | matthew | 2018/08/19 06:58 PM |
Remote atomics | anon | 2018/08/19 11:59 PM |
Remote atomics | Travis | 2018/08/20 09:26 AM |
Remote atomics | Travis | 2018/08/20 08:57 AM |
Remote atomics | Linus Torvalds | 2018/08/20 03:29 PM |
Fitting time slices to execution phases | Paul A. Clayton | 2018/08/21 08:09 AM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 01:34 PM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 02:31 PM |
Fitting time slices to execution phases | Gabriele Svelto | 2018/08/21 02:54 PM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 03:26 PM |
Fitting time slices to execution phases | Travis | 2018/08/21 03:21 PM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 03:39 PM |
Fitting time slices to execution phases | Travis | 2018/08/21 03:59 PM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 04:13 PM |
Fitting time slices to execution phases | anon | 2018/08/21 03:27 PM |
Fitting time slices to execution phases | Linus Torvalds | 2018/08/21 05:02 PM |
Fitting time slices to execution phases | Etienne | 2018/08/22 01:28 AM |
Fitting time slices to execution phases | Gabriele Svelto | 2018/08/22 02:07 PM |
Fitting time slices to execution phases | Travis | 2018/08/22 03:00 PM |
Fitting time slices to execution phases | anon | 2018/08/22 05:52 PM |
Fitting time slices to execution phases | Travis | 2018/08/21 03:37 PM |
Is preventing misuse that complex? | Paul A. Clayton | 2018/08/23 04:42 AM |
Is preventing misuse that complex? | Linus Torvalds | 2018/08/23 11:46 AM |
Is preventing misuse that complex? | Travis | 2018/08/23 12:29 PM |
Is preventing misuse that complex? | Travis | 2018/08/23 12:33 PM |
Is preventing misuse that complex? | Jeff S. | 2018/08/24 06:57 AM |
Is preventing misuse that complex? | Travis | 2018/08/24 07:47 AM |
Is preventing misuse that complex? | Linus Torvalds | 2018/08/23 01:30 PM |
Is preventing misuse that complex? | Travis | 2018/08/23 02:11 PM |
Is preventing misuse that complex? | Linus Torvalds | 2018/08/24 12:00 PM |
Is preventing misuse that complex? | Gabriele Svelto | 2018/08/24 12:25 PM |
Is preventing misuse that complex? | Linus Torvalds | 2018/08/24 12:33 PM |
Fitting time slices to execution phases | Travis | 2018/08/21 02:54 PM |
rseq: holy grail rwlock? | Travis | 2018/08/21 02:18 PM |
rseq: holy grail rwlock? | Linus Torvalds | 2018/08/21 02:59 PM |
rseq: holy grail rwlock? | Travis | 2018/08/21 03:27 PM |
rseq: holy grail rwlock? | Linus Torvalds | 2018/08/21 04:10 PM |
rseq: holy grail rwlock? | Travis | 2018/08/21 05:21 PM |
ARM design houses | Michael S | 2018/08/21 04:07 AM |
ARM design houses | Wilco | 2018/08/22 11:38 AM |
ARM design houses | Michael S | 2018/08/22 01:21 PM |
ARM design houses | Wilco | 2018/08/22 02:23 PM |
ARM design houses | Michael S | 2018/08/29 12:58 AM |
Qualcomm's core naming scheme really, really sucks | Heikki Kultala | 2018/08/29 01:19 AM |
A76 | Maynard Handley | 2018/08/18 01:07 PM |
A76 | Michael S | 2018/08/18 01:32 PM |
A76 | Maynard Handley | 2018/08/18 01:52 PM |
A76 | Michael S | 2018/08/18 02:04 PM |
ARM is somewhat misleading | juanrga | 2018/08/17 12:20 AM |
Surprised?? | Alberto | 2018/08/17 12:52 AM |
Surprised?? | Alberto | 2018/08/17 01:10 AM |
Surprised?? | none | 2018/08/17 01:46 AM |
Garbage talk | Andrei Frumusanu | 2018/08/17 06:30 AM |
Garbage talk | Michael S | 2018/08/17 06:43 AM |
Garbage talk | Andrei Frumusanu | 2018/08/17 08:51 AM |
Garbage talk | Michael S | 2018/08/18 10:29 AM |
Garbage talk | Adrian | 2018/08/17 07:28 AM |
Garbage talk | Alberto | 2018/08/17 08:20 AM |
Garbage talk | Andrei Frumusanu | 2018/08/17 08:48 AM |
Garbage talk | Adrian | 2018/08/17 09:17 AM |
Garbage talk | Andrei Frumusanu | 2018/08/17 09:36 AM |
Garbage talk | Adrian | 2018/08/17 01:53 PM |
Garbage talk | Andrei Frumusanu | 2018/08/17 11:17 PM |
More like a religion he?? ARM has an easy life :) | Alberto | 2018/08/17 08:13 AM |
More like a religion he?? ARM has an easy life :) | Andrei Frumusanu | 2018/08/17 08:34 AM |
More like a religion he?? ARM has an easy life :) | Alberto | 2018/08/17 09:03 AM |
More like a religion he?? ARM has an easy life :) | Andrei Frumusanu | 2018/08/17 09:43 AM |
More like a religion he?? ARM has an easy life :) | Doug S | 2018/08/17 01:17 PM |
15W phone SoCs | AM | 2018/08/17 02:04 PM |
More like a religion he?? ARM has an easy life :) | Maynard Handley | 2018/08/17 11:29 AM |
my future stuff will be better than your old stuff, hey I'm a god at last (NT) | Eric Bron | 2018/08/18 02:34 AM |
my future stuff will be better than your old stuff, hey I'm a god at last | none | 2018/08/18 07:34 AM |