Networking

By: Wilco (Wilco.Dijkstra.delete@this.ntlworld.com), September 20, 2009 5:11 am
Room: Moderated Discussions
David Kanter (dkanter@realworldtech.com) on 9/19/09 wrote:
---------------------------
>Wilco (Wilco.Dijkstra@ntlworld.com) on 9/19/09 wrote:
>---------------------------
>>David Kanter (dkanter@realworldtech.com) on 9/19/09 wrote:
>>---------------------------
>>>Wilco (Wilco.Dijkstra@ntlworld.com) on 9/19/09 wrote:
>>>---------------------------
>>>>David Kanter (dkanter@realworldtech.com) on 9/18/09 wrote:
>>>>---------------------------
>>>>>To achieve the performance of a 2S Nehalem, you're going to need a ton of ARMs.
>>>>>And they all need to have ethernet to communicate. Those cables are not free and
>>>>>use space and power, as do the switches they connect to.
>>>>
>>>>The current Cortex-A9 doesn't compete with Nehalem indeed. However the gap with
>>>>x86 is closing fast, and I'd expect the next generation to be far closer.
>>>>
>>>>What low power enables is packing many sockets in a single rack - 8-16 sockets
>>>>should be possible. As long as they can talk to each other, you don't need more
>>>>than 1 network connection per board.
>>>
>>>So how do you want them to talk? Coherency for 16S isn't trivial (look how long
>>>it took intel to get there), and if it's not coherent and you are using a network
>>>stack...then you still need an on-board switch of some sort.
>>
>>ARM doesn't have something like HyperTransport, and the market is too small to
>>be worth adding inter-socket coherency.
>
>Agreed.
>
>>So you could use an on-board switch and
>>use an ethernet connection in each socket, or run the >network stack on one socket,
>>and DMA the packets to the relevant cores via a fast >serial link.
>
>So basically you are thinking of using something like XAUI between chips?
>
>I guess the thing that makes me leery is that network overhead may not be small for an ARM, but who knows.

Something like that, yes. Basically anything that allows one to reuse an existing chip with ethernet support and connect it with other chips on the same circuit board without needing bulky connectors and cables.

Why do you think network overhead is large on ARM? If anything, ARM is very well suited to networking, given it has DMA, unaligned access, seamless little/big endian, fast interrupts etc. Even very low-end ARMs have ethernet ports.

>>>>Assuming a conservative 2 boards, 8 sockets, 4 cores per >socket, you could have
>>>>64 cores in a 1U rack (ie. 8 times more than a typical 2S >quad core today).
>>>
>>>That's still a lot of hypothetical infrastructure. 2S x86s exist today, and they will have 12 cores per socket soon.
>>
>>It's an interesting thought experiment though - all it >needs is a startup making
>>it happen.
>
>Right...so my opinion is that whoever funds a start up like would be crazy.
>
>You can't go for HPC, because NV and ATI will just crush you in efficiency.

Based on what evidence? The Cortex-A9 is twice as efficient in DP FLOPS/W as the most efficient chip in your efficiency article. And that for a chip not optimized for DP performance... (SP is 5 times as fast)

The datapoint for your efficiency graph is 3.2GFLOPS/W, ~0.35GFLOPS/mm^2 for the 2GHz dual core, and 4.8GFLOPS/W, ~0.16GFLOPS/mm^2 for the 800MHz version.

>You're probably stuck going after the same markets that Afara was, and they didn't
>seem to do so well. Admittedly, you can go for a lower budget since you aren't taping out a chip.
>
>There are probably a couple of companies doing what you're suggesting, but I don't know if they are using ARM.

Probably not yet, as until quite recently there were no 1+GHz ARMs. ARM, Marvell, Qualcomm all have fast superscalar and OoO designs coming out later this year or next year.

>> How much power does a 12 core x86 chip use? Frequency >would be below
>>2GHz for a reasonable power budget. Not being power >limited allows ARM to close the performance gap even >quicker.
>
>AMD will probably hit 2GHz, and keep in mind, the cores are quite beefy there.
>Not sure how they compare in specint to ARM.

Unfortunately running SPEC on embedded cores is difficult, especially since it requires a full system with multiple gigabytes of memory and storage, so one typically uses smaller benchmarks like EEMBC. On Coremark (www.coremark.org) Cortex-A9 beats Phenom II per MHz. Core 2 is about 40% faster.

Wilco
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
ARM announces 2GHz netbook CPUWilco2009/09/16 11:00 AM
  ARM announces 2GHz netbook CPURichard Cownie2009/09/16 03:51 PM
  ARM announces 2GHz netbook CPUPotatoswatter2009/09/16 04:12 PM
  ARM announces 2GHz netbook CPUMegol2009/09/16 04:21 PM
    ARM announces 2GHz netbook CPUWilco2009/09/18 01:13 AM
      ARM announces 2GHz netbook CPUMegol2009/09/18 11:54 AM
  ARM announces 2GHz netbook CPUsomeone2009/09/16 06:01 PM
  ARM announces 2GHz netbook CPUSeni2009/09/16 06:41 PM
    ARM announces 2GHz netbook CPUsomeone2009/09/16 07:32 PM
      ARM announces 2GHz netbook CPUanon2009/09/16 08:58 PM
      ARM announces 2GHz netbook CPUDavid Kanter2009/09/17 04:53 AM
        ARM announces 2GHz netbook CPUsomeone2009/09/17 06:10 AM
          ARM announces 2GHz netbook CPUDavid Kanter2009/09/17 03:02 PM
            ARM announces 2GHz netbook CPUanon2009/09/20 05:34 PM
      ARM announces 2GHz netbook CPUSeni2009/09/17 02:05 PM
        ARM announces 2GHz netbook CPUWilco2009/09/17 03:29 PM
          ARM announces 2GHz netbook CPUSeni2009/09/17 03:53 PM
            ARM announces 2GHz netbook CPUWilco2009/09/17 11:31 PM
              ARM announces 2GHz netbook CPUDavid Kanter2009/09/18 04:17 PM
  ARM announces 2GHz netbook CPUJouni Osmala2009/09/16 09:40 PM
    ARM announces 2GHz netbook CPUMartin Høyer Kristiansen2009/09/17 01:15 AM
      ARM announces 2GHz netbook CPUWilco2009/09/18 01:56 AM
        ARM announces 2GHz netbook CPUJouni Osmala2009/09/18 04:46 AM
          ARM announces 2GHz netbook CPUMichael S2009/09/18 06:22 AM
          ARM announces 2GHz netbook CPUWilco2009/09/18 11:36 AM
            ARM announces 2GHz netbook CPUrcf2009/09/19 08:49 AM
              The other sides of the coin?2009/09/19 11:09 AM
                The other sides of the coinPaul2009/09/20 02:30 AM
                  The other sides of the coinJukka Larja2009/09/20 10:20 PM
          ARM announces 2GHz netbook CPUAM2009/09/19 03:41 AM
        ARM announces 2GHz netbook CPUMichael S2009/09/18 05:15 AM
        ARM announces 2GHz netbook CPUMichael S2009/09/18 05:48 AM
          ARM announces 2GHz netbook CPUWilco2009/09/18 01:15 PM
            ARM announces 2GHz netbook CPUMichael S2009/09/20 09:00 AM
              ARM announces 2GHz netbook CPULinus Torvalds2009/09/20 09:59 AM
                ARM announces 2GHz netbook CPUMichael S2009/09/20 10:42 AM
                  ARM announces 2GHz netbook CPULinus Torvalds2009/09/20 02:19 PM
                    ARM announces 2GHz netbook CPUMichael S2009/09/20 03:12 PM
                    ARM announces 2GHz netbook CPUanonymous2009/09/20 04:58 PM
                      ARM announces 2GHz netbook CPUMichael S2009/09/21 02:49 AM
                        ARM announces 2GHz netbook CPUWilco2009/09/21 03:38 AM
                          ARM announces 2GHz netbook CPULinus Torvalds2009/09/21 07:05 AM
                            ARM announces 2GHz netbook CPUnone2009/09/21 07:10 AM
                              ARM announces 2GHz netbook CPULinus Torvalds2009/09/21 08:24 AM
                                ARM announces 2GHz netbook CPUIntelUser20002009/09/21 06:59 PM
                                  ARM announces 2GHz netbook CPULinus Torvalds2009/09/21 07:15 PM
                    Atom-based Octane IIIDavid Wragg2009/09/22 04:11 AM
                      Atom-based Octane IIIArun Ramakrishnan2009/09/22 10:02 PM
                        Many Atoms -> Molecule ? :-) (NT)Anon42009/09/23 03:49 AM
                          Many Atoms -> Molecule ? :-) (NT)Arun Ramakrishnan2009/09/23 04:11 AM
            Scalar DFlops/HzMichael S2009/09/20 12:00 PM
              Scalar DFlops/HzWilco2009/09/20 12:45 PM
                VMLA.f64 Michael S2009/09/20 01:46 PM
                  VMLA.f64 Paul2009/09/20 02:16 PM
                  VMLA.f64 Wilco2009/09/20 04:45 PM
        ARM announces 2GHz netbook CPUDavid Kanter2009/09/18 04:19 PM
  Who wants an ARM netbook?slacker2009/09/17 12:05 AM
    Who wants an ARM netbook?slacker2009/09/17 12:21 AM
    Who wants an ARM netbook?Wilco2009/09/17 02:10 AM
      Who wants an ARM netbook?xxx2009/09/17 02:31 AM
        Who wants an ARM netbook?Wilco2009/09/17 03:04 AM
          Who wants an ARM netbook?Hello2009/09/21 06:47 AM
            Who wants an ARM netbook?none2009/09/21 09:04 AM
              Who wants an ARM netbook?Wilco2009/09/21 02:12 PM
                Who wants an ARM netbook?Hello2009/09/22 02:46 AM
    Who wants an ARM netbook?Gian-Carlo Pascutto2009/09/17 02:24 AM
      Who wants an ARM netbook?slacker2009/09/17 04:28 AM
        Who wants an ARM netbook?Gian-Carlo Pascutto2009/09/17 05:23 AM
        Who wants an ARM netbook?rcf2009/09/17 06:58 AM
    Who wants an ARM netbook?Cooper2009/09/17 03:33 PM
      Who wants an ARM netbook?anon2009/09/17 05:32 PM
        Who wants an ARM netbook?anon2009/09/17 10:50 PM
    Who wants an ARM netbook?Howard Chu2009/09/17 08:48 PM
    Who wants an ARM netbook?Foo_2009/09/21 03:44 AM
  ARM for serverKISS2009/09/17 06:13 AM
    ARM for serverLinus Torvalds2009/09/17 06:57 AM
      ARM for serverAdrian2009/09/17 08:04 AM
        ARM for serverRichard Cownie2009/09/17 08:19 AM
          ARM for serverAdrian2009/09/17 08:49 AM
            Let's talk about an ARM-inside big machineKISS2009/09/17 09:08 AM
              Let's talk about an ARM-inside big machineanon2009/09/17 09:44 AM
                Let's talk about an ARM-inside big machineRichard Cownie2009/09/17 11:00 AM
                  article about google serverRichard Cownie2009/09/17 11:04 AM
                  Let's talk about an ARM-inside big machineanon2009/09/17 11:28 AM
                    Let's talk about an ARM-inside big machineRichard Cownie2009/09/17 11:47 AM
                      Let's talk about an ARM-inside big machineanon2009/09/17 10:31 PM
                NetworkingDavid Kanter2009/09/18 05:13 PM
                  NetworkingWilco2009/09/19 01:35 AM
                    NetworkingPaul2009/09/19 05:47 AM
                    Networkinganon2009/09/19 06:03 AM
                    NetworkingDavid Kanter2009/09/19 02:04 PM
                      NetworkingWilco2009/09/19 03:15 PM
                        NetworkingDavid Kanter2009/09/19 03:37 PM
                          NetworkingWilco2009/09/20 05:11 AM
              Let's talk about an ARM-inside big machinea reader2009/09/17 01:28 PM
              Let's talk about an ARM-inside big machineA. No. Nymous2009/09/24 04:48 PM
                Let's talk about an ARM-inside big machineHoward Chu2009/09/24 10:19 PM
                Let's talk about an ARM-inside big machineKISS2009/09/26 12:06 AM
            Screen resolutionsRob Thorpe2009/09/18 10:09 AM
              Screen resolutionsHoward Chu2009/09/18 12:32 PM
        ARM for serverGroo2009/09/17 12:15 PM
          ARM for serverRichard Stacpoole2009/09/17 02:49 PM
            ARM for serverRichard Cownie2009/09/17 06:35 PM
              ARM for serverRichard Stacpoole2009/09/17 09:21 PM
                ARM for serverLinus Torvalds2009/09/18 06:33 AM
                  ARM for serverMichael S2009/09/18 07:15 AM
                  ARM for serverRichard Cownie2009/09/18 07:56 AM
                  ARM for serverslacker2009/09/18 03:50 PM
                    causes of mechanical stressRichard Cownie2009/09/18 04:27 PM
                      causes of mechanical stressslacker2009/09/18 05:42 PM
                        causes of mechanical stressRichard Cownie2009/09/18 06:06 PM
                          causes of mechanical stressHoward Chu2009/09/18 06:14 PM
                            causes of mechanical stressRichard Cownie2009/09/18 07:33 PM
                              causes of mechanical stressHoward Chu2009/09/18 09:31 PM
                            causes of mechanical stressAnin2009/09/19 10:28 PM
                              causes of mechanical stressMegol2009/09/22 06:58 AM
                          causes of mechanical stressslacker2009/09/18 08:13 PM
                            causes of mechanical stressRichard Cownie2009/09/18 08:52 PM
                              causes of mechanical stressDavid Kanter2009/09/18 10:31 PM
                              causes of mechanical stressUngo2009/09/22 04:34 PM
                                causes of mechanical stressRichard Cownie2009/09/23 10:00 AM
                        causes of mechanical stressLinus Torvalds2009/09/19 08:44 AM
                          causes of mechanical stressRichard Cownie2009/09/19 11:24 AM
                          causes of mechanical stressslacker2009/09/19 04:33 PM
                          anecdotal lack of reliability of Macskdg2009/09/21 12:08 PM
                            anecdotal lack of reliability of Macsanon2009/09/22 09:30 AM
                              anecdotal lack of reliability of Macskdg2009/09/22 11:33 AM
                    ARM for serverAnon2009/09/18 07:35 PM
                      ARM for serveranon2009/09/18 08:20 PM
                        ARM for serverRagingDragon2009/09/19 12:33 PM
                          ARM for serveranon2009/09/20 11:29 AM
                        ARM for serverAnon2009/09/19 02:29 PM
                          ARM for serveranon2009/09/20 11:24 AM
                            ARM for serverRagingDragon2009/09/20 02:16 PM
                              [O.T.] "carbon steel"Michael S2009/09/20 03:45 PM
                                [O.T.] "carbon steel"slacker2009/09/20 05:04 PM
                                [O.T.] "carbon steel"RagingDragon2009/09/21 09:42 PM
                                  [O.T.] "carbon steel"Michael S2009/09/22 12:36 AM
                            ARM for serverAnon2009/09/20 06:52 PM
                              ARM for serveranon2009/09/26 07:56 AM
                          ARM for serverUngo2009/09/22 04:25 PM
                            ARM for serverRagingDragon2009/09/23 11:13 AM
                              ARM for serverCarlie Coats2009/09/24 09:28 AM
                      ARM for serverslacker2009/09/18 08:24 PM
                  ARM for serverRichard Stacpoole2009/09/18 05:34 PM
                  ARM for serverJukka Larja2009/09/18 09:17 PM
                    ARM for serverMegol2009/09/19 02:18 AM
                ARM for serverRichard Cownie2009/09/18 07:31 AM
                  ARM for serverRichard Stacpoole2009/09/18 05:18 PM
                    ARM for serverRichard Cownie2009/09/18 09:20 PM
                      ARM for serverRichard Stacpoole2009/09/19 12:02 AM
                        ARM for serverRichard Cownie2009/09/19 03:57 AM
                          ARM for serverRichard Stacpoole2009/09/19 04:24 AM
                            ARM for serverRichard Cownie2009/09/19 07:12 AM
                  ARM for serverJukka Larja2009/09/18 09:57 PM
          ARM for serverMark Christiansen2009/09/18 03:17 PM
      Cortex performanceTom W2009/09/19 08:52 AM
        Cortex performanceanon2009/09/19 09:50 AM
        Cortex performanceHoward Chu2009/09/19 11:57 AM
          Cortex performanceHoward Chu2009/09/19 12:05 PM
            Cortex performanceWilco2009/09/19 01:38 PM
              Cortex performanceHoward Chu2009/09/20 10:59 PM
  No silicon yet?someone2009/09/17 12:18 PM
    No silicon yet?anon2009/09/18 12:06 AM
      No silicon yet?anon2009/09/18 07:30 AM
      No silicon yet?Hello2009/09/21 07:38 AM
        No silicon yet?anon2009/09/21 12:44 PM
          No silicon yet?none2009/09/21 11:54 PM
            No silicon yet?Wilco2009/09/22 01:24 AM
              No silicon yet??2009/09/22 11:18 AM
                No silicon yet?IntelUser20002009/09/22 12:13 PM
                No silicon yet?none2009/09/22 01:40 PM
                  No silicon yet?Wilco2009/09/22 02:53 PM
                    No silicon yet?a reader2009/09/23 07:45 AM
                  No silicon yet??2009/09/22 11:34 PM
  Why China Mobile choose Marvell PXA920?Michael S2009/09/22 02:49 AM
    Why China Mobile choose Marvell PXA920?Wilco2009/09/22 02:23 PM
      Why China Mobile choose Marvell PXA920?Michael S2009/09/22 02:46 PM
        Why China Mobile choose Marvell PXA920?Wilco2009/09/22 03:03 PM
          Why China Mobile choose Marvell PXA920?Michael S2009/09/22 04:48 PM
    Why China Mobile choose Marvell PXA920?Paul2009/09/22 05:46 PM
      Why China Mobile choose Marvell PXA920?Anon42009/09/23 03:53 AM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell avocado?