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The Mac Pro isn't a great value in the datacenter space. It's a single socket server that's limited to 64 GB of RAM. It's not unusual anymore to throw GPUs in r

by exelius 12y ago

The Mac Pro isn't a great value in the datacenter space. It's a single socket server that's limited to 64 GB of RAM. It's not unusual anymore to throw GPUs in rack mount systems; most of them already have the PCIe bandwidth necessary to support 4 big GPUs so it's often just a matter of getting the right riser cards. Compare a Mac Pro to an HP DL360 that can hold 4 8-core Xeons (32 cores total) and over 200GB of RAM along with a few FirePro or Titan GPGPUs, and the HP will give you far greater density (though a rack mount system with 4 8-core Xeons and 4 GTX Titans would be a power and cooling nightmare!). That said, the Mac Pro isn't as far behind as I would have expected. But OS X also kicks ass at multithreading, especially if you use Apple's graphics libraries. It's entirely possible they get much greater performance from OS X than a Linux or Windows based solution could provide.

robbyt 12y ago
OS X does not have NUMA. It has some nice libraries for multi-threading, but that doesn't really matter that much when you're saturating your memory bus because the CPUs are doing too many cross-zone memory requests.
- exelius 12y ago
  NUMA is irrelevant anyway because there are currently no multi-socket OS X machines. Multiple cores on the same package share a memory controller.
  - deleted 12y ago
    [deleted]
- acdha 12y ago
  While OS X doesn't have something like Linux's NUMA interface to explicitly lock a thread to a core, 10.5 shipped a thread affinity API which allows you to help the scheduler make better placement decisions: “OS X does not export interfaces that identify processors or control thread placement—explicit thread to processor binding is not supported. Instead, the kernel manages all thread placement. Applications expect that the scheduler will, under most circumstances, run its threads using a good processor placement with respect to cache affinity. However, the application itself knows the detailed caching characteristics of its threads and its data—in particular, the organization of threads as disjoint sets characterized by their association with (affinity to) distinct shared data. While threads within such a set exhibit affinity with each other via shared data, they share a disaffinity or negative affinity with respect to other sets. In other words, a set expresses an affinity with an L2 cache and the scheduler should seek to run threads in a set on processors sharing that L2 cache.” https://developer.apple.com/library/mac/releasenotes/Performance/RN-AffinityAPI/ https://developer.apple.com/library/mac/releasenotes/Perform...
mozumder 12y ago
Well, they're fitting 4 sockets and 8 GPUS in the space that's normally used by 4 sockets only. Also, if you're trying to sync raw images between OS X clients and the cloud, then you're going to need OS X servers in the cloud. It'll greatly complicate the clients workflow if they can't use their built in raw converters.
- exelius 12y ago
  Right; which is why I was surprised that OS X stacks up as favorably as it does. But I wouldn't call it a great value since it's still much more expensive than a traditional rack mount setup. From a density perspective it's really not bad at all, which is a testament to how well-engineered the Mac Pro is.
  - mozumder 12y ago
    I'd say it's not even as expensive as something like IBM's 4-socket rack servers like the x3850 X6.
    - exelius 12y ago
      Yeah, except IBM's x86 hardware has always been stupid expensive for no good reason other than it's IBM. And didn't they spin off their xSeries server business to Lenovo once the market settled on HP systems that cost half what IBM's did?
      - mozumder 12y ago
        Even an HP 4 socket system like the DL980 G7 is going to be as expensive. None of these servers are going to be cheap.
        rconti 12y ago
        Also the DL980 G7 is an unholy piece of crap. HP doesn't know how to build or fix them. I've gone through countless service requests on just a dozen machines or thereabouts. It's the worst piece of any kind of hardware I've ever used, hands down.
semi-extrinsic 12y ago
No sane person is putting GTX cards into a configuration with that level of power density, you'd have reliability issues from day one. This use case is exactly why Nvidia makes Tesla cards.
lectrick 12y ago
The manager of the datacenter kicked in a comment 9 minutes ago or so defending the decision (with facts) at the same level of your comment, if you want to check that out.

by exelius 12y ago

robbyt 12y ago

OS X does not have NUMA. It has some nice libraries for multi-threading, but that doesn't really matter that much when you're saturating your memory bus because the CPUs are doing too many cross-zone memory requests.

exelius 12y ago
NUMA is irrelevant anyway because there are currently no multi-socket OS X machines. Multiple cores on the same package share a memory controller.
- deleted 12y ago
  [deleted]
acdha 12y ago
While OS X doesn't have something like Linux's NUMA interface to explicitly lock a thread to a core, 10.5 shipped a thread affinity API which allows you to help the scheduler make better placement decisions: “OS X does not export interfaces that identify processors or control thread placement—explicit thread to processor binding is not supported. Instead, the kernel manages all thread placement. Applications expect that the scheduler will, under most circumstances, run its threads using a good processor placement with respect to cache affinity. However, the application itself knows the detailed caching characteristics of its threads and its data—in particular, the organization of threads as disjoint sets characterized by their association with (affinity to) distinct shared data. While threads within such a set exhibit affinity with each other via shared data, they share a disaffinity or negative affinity with respect to other sets. In other words, a set expresses an affinity with an L2 cache and the scheduler should seek to run threads in a set on processors sharing that L2 cache.” https://developer.apple.com/library/mac/releasenotes/Performance/RN-AffinityAPI/ https://developer.apple.com/library/mac/releasenotes/Perform...

mozumder 12y ago

Well, they're fitting 4 sockets and 8 GPUS in the space that's normally used by 4 sockets only. Also, if you're trying to sync raw images between OS X clients and the cloud, then you're going to need OS X servers in the cloud. It'll greatly complicate the clients workflow if they can't use their built in raw converters.

exelius 12y ago
Right; which is why I was surprised that OS X stacks up as favorably as it does. But I wouldn't call it a great value since it's still much more expensive than a traditional rack mount setup. From a density perspective it's really not bad at all, which is a testament to how well-engineered the Mac Pro is.
- mozumder 12y ago
  I'd say it's not even as expensive as something like IBM's 4-socket rack servers like the x3850 X6.
  - exelius 12y ago
    Yeah, except IBM's x86 hardware has always been stupid expensive for no good reason other than it's IBM. And didn't they spin off their xSeries server business to Lenovo once the market settled on HP systems that cost half what IBM's did?
    - mozumder 12y ago
      Even an HP 4 socket system like the DL980 G7 is going to be as expensive. None of these servers are going to be cheap.
      - rconti 12y ago
        Also the DL980 G7 is an unholy piece of crap. HP doesn't know how to build or fix them. I've gone through countless service requests on just a dozen machines or thereabouts. It's the worst piece of any kind of hardware I've ever used, hands down.

semi-extrinsic 12y ago

No sane person is putting GTX cards into a configuration with that level of power density, you'd have reliability issues from day one. This use case is exactly why Nvidia makes Tesla cards.

lectrick 12y ago

The manager of the datacenter kicked in a comment 9 minutes ago or so defending the decision (with facts) at the same level of your comment, if you want to check that out.