IBM 71413SU - System x3950 M2 Reference

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IBM System x3950 M2 and x3850 M2 Technical Introduction 21Applications that run in full 64-bit mode will have access to the full physical memoryrange, depending on the operating system, and will also have access to the new GPRsas well as to the expanded GPRs. However, it is important to understand that thismode of operation requires not only a 64-bit operating system (and, of course, 64-bitdrivers) but also a 64-bit application that has been recompiled to take full advantage ofthe various enhancements of the 64-bit addressing architecture.For more information about the features of the Xeon quad-core processor, see:http://www.intel.com/products/server/processors/index.htm?iid=process+serverFor more information about Intel 64, see:http://www.intel.com/technology/architecture-silicon/intel64/index.htmXceL4v Dynamic Server CacheThe XceL4v Dynamic Server Cache is a technology developed as part of the IBM XA-64efourth-generation chipset. It is used in two ways: As a single 4-way server, the XceL4v and its embedded DRAM (eDRAM) is used as asnoop filter to reduce traffic on the front-side bus. It stores a directory of all processorcache lines to minimize snoop traffic on the four front-side buses and minimize cachemisses. When the x3950 M2 is configured as a multinode server, this technology dynamicallyallocates 256 MB of main memory in each node for use as an L4 cache directory andscalability directory. In an 8-way configuration, this means there will be 512 MB of XceL4vcache.Used in conjunction with the XceL4v Dynamic Server Cache is an embedded DRAM(eDRAM), which in single-node configurations contains the snoop filter lookup tables.However, in a multinode configuration, this eDRAM contains the L4 cache directory and thescalability directory.System memoryThe x3850 M2 and x3950 M2 models have either 4 GB or 8 GB of RAM standard,implemented as four or eight 1 GB DIMMs. Memory is PC2-5300 ECC DDR2.Memory is implemented in the x3850 M2 and x3950 M2 using memory cards. The serversupports up to four memory cards. Each card has eight DIMM sockets, giving a total of up to32 DIMM sockets. Some models have two memory cards and some have all four cardsstandard. Table 3 on page 12 provides more detail about this topic.Using 8 GB DIMMs in every socket, the server can hold 256 GB of RAM. With four nodes, thecombined complex can hold up to 1 TB of RAM.With a multinode configuration, the memory in all nodes is combined to form a single,coherent physical address space. The resulting system has the property such that for anygiven region of physical memory, some processors are closer to it than other processors.Note: The amount of memory that BIOS reports is minus the portion used for XceL4vcache.