DRAM Power Mode option, not found. Why?

Discussion in 'BIOS Optimization Guide (BOG)' started by portillo, Mar 28, 2013.

  1. portillo

    portillo Newbie

    Hello TechArp community! :wave:

    Currently I'm doing research related to power consumption optimizations for heterogeneous systems (systems with processors & co-processors -> Like a GPGPU). And I'm interested on what impact does the Memory page mode (in specific open and closed page modes) has for several classes of applications, executed on one of these systems.

    The BIOS (described under) installed on the selected motherboard does not provide the option to enable or disable the DRAM page mode (in contrast to Award BIOS), and I would like to know if there is a way to change this value. If there is no way to change it, it would help to know which DRAM page mode comes as default and maybe why.

    Compute system basic information:

    Mobo: SuperMicro X8DAH+-F
    BIOS: SuperMicro X8DAH V.2.1 (Built 12/30/2011)
    Memory: Samsung DDR3 @ 1333 MHz, 4GB, 64 bits data width.

    Thank you, for your time.
  2. portillo

    portillo Newbie

    More information

    Probably more information about the system in question, could help.

    Chipset: Intel 5520 (Tylersburg) ICH10R +2x IOH-36D
    Processor: 2 x Intel Xeon X5650

  3. portillo

    portillo Newbie

    I messed up the title

    Instead of
    DRAM Power Mode ...
    DRAM Page Mode ...
  4. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hi portillo,

    Server chipsets use the closed page policy, because it allows for faster random accesses to different rows, which is the usual access pattern for servers.

    The memory access performance will suffer, and its power consumption would increase, if the IMC used the open page policy instead.
  5. portillo

    portillo Newbie

    As far as I know, the performance affected by open- or closed-page mode is application dependent. You stated that servers chipsets use closed page policy, which makes sense as usually there are many threads executing concurrently and access to memory is more random (e.g., accessing pages in different row locations). How did you knew that server's chipsets use such page policy?

    Is possible (at least from the theory point of view) to reduce power consumption and increase performance if we use open-page mode with a memory bound application (e.g., Naive-matrix transpose), and the opposite if using closed-page mode. Right now, I'm focusing in the open-page mode. Do you know if there is a way to change these parameters?

    Do you know where is the location of the IMC? I know there is one embedded in the CPU (at least for Intel - Sandy Bridge and above). Is there another one? Which MC does the PCIe use?

    Any documentation would help, thanks!
  6. Adrian Wong

    Adrian Wong Da Boss Staff Member

    As I recall, the page policy is fixed at least the BIOS level, if not the chipset itself. At least I haven't seen any BIOS options to change it. The page policy for the MCH should be mentioned in its datasheet.

    In server situations, I don't think changing the page policy will result in significant savings in power consumption.

    In current Intel processors, the memory and PCIe controllers are part of the processor, not on a separate chip.
  7. portillo

    portillo Newbie

    On Tom's Hardware I have seen MoBos which have the option in their BIOS to use open or close page. I tried you suggestion to find the MCH in the datasheet of the MoBo I'm using, without success... =/

    I'm researching this towards embedded systems, not towards servers. Furthermore, these systems execute the same software all their life span, thus saving half a Watt per execution will add up to considerable power savings...

    Specially thanks for this info -> "the memory and PCIe controllers are part of the processor, not on a separate chip" that explains why I'm seeing so much CPU usage even when I'm doing DMA data transfers between main memory and a co-processor (GPU)...

    Thanks... I guess this is not possible after all..
  8. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Which motherboards did you see on Tom's that had the BIOS option to change between open and closed pages? Thanks!
  9. portillo

    portillo Newbie

    Basically most of the MotherBoards that can handle the Award BIOS firmware... Thanks to you as well!

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