SPEC CPU2006 Flag Description for NEC Server Platform
- Zone Reclaim:
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Zone reclaim allows the reclaiming of pages from a zone if the number of free pages
falls below a watermark even if other zones still have enough pages available.
Reclaiming a page can be more beneficial than taking the performance penalties that
are associated with allocating a page on a remote zone, especially for NUMA machines.
- Memory RAS Mode:
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The server has RAS feature including "Independent", "Independent + Rank Sparing", "Independent + Mirroring", "Lock Step,
"Lock Step + Rand Sparing", "Lock Step + Mirroring", and "Memory Scrubbing" modes.
- Independent mode: In "Independent" mode, the four memory channels operate independently. It supports ECC correction (64-Bit Data + 8-Bit ECC)
and SDDC (Single Device Data Correction) that corrects an error to a single DRAM.
Memory performance is higher than LockStep mode, however, RAS feature is rather poor.
- Independent + Rank Sparing mode: In "Independent + Rank Sparing" mode, spare ranks are added to Independent mode. If the indication of failure
is detected in running rank, replace the data by copying it onto spare rank on the same channel to continue processing.
RAS feature is higher than Independent mode, however, the memory capacity available for OS is reduced by the amount of memory
used for spare rank from the installed memory.
- Independent + Mirroring: In "Independent + Mirroring" mode, mirroring memory is added to Independent mode, and regularly copies the contents
of memory onto mirroring memory. If the memory error is detected, the mirroring memory takes over to continue processing.
RAS feature is higher than Independent mode and "Independent + Rank Sparing" mode, however, the memory capacity available for OS is reduced
to half of installed memory capacity.
- Lock Step mode: In "Lock Step" mode, a pair of two memory channels is used to perform 128-bit data access. It supports ECC correction (128-bit
Data + 16-Bit ECC) and DDDC (Double Device Data Correction) that can correct double DRAM errors.
Memory performance is lower than Independent mode, however, RAS feature is higher than Independent mode.
- Lock Step + Rank Sparing mode: In "Lock Step + Rank Sparing" mode, spare ranks are added to Lock Step mode. If the indication of failure
is detected in running rank, replace the data in unit of Lock Step PAIR by copying it onto spare rank on the same channel to continue processing.
RAS feature is higher than Lock Step mode, however, the memory capacity available for OS is reduced by the capacity of spare rank from the installed memory.
- LockStep + Mirroring mode: In "LockStep + Mirroring" mode, mirroring memory is added to Lock Step mode, and regularly copies the contents
of memory onto mirroring memory. If the memory error is detected, the mirroring memory takes over to continue processing.
RAS feature is higher than LockStep mode and "LockStep + Rank Sparing" mode, however, the memory capacity available for OS is reduced
to half of installed memory capacity.