A question came up recently about my choice of definitions for “MB” used in the computation of memory bandwidth (in “MB/s”) in the STREAM benchmark. According to this reference from NIST, the convention is: Binary Powers Value abbreviation full name 2^10 1,024 KiB kibibyte 2^20 1,048,576 MiB mebibyte 2^30 1,073,741,824… read more
Performance
What good are “Large Pages” ?
I am often asked what “Large Pages” in computer systems are good for. For commodity (x86_64) processors, “small pages” are 4KiB, while “large pages” are (typically) 2MiB. The size of the page controls how many bits are translated between virtual and physical addresses, and so represent a trade-off between what… read more
Is “ordered summation” a hard problem to speed up?
Sometimes things that seem incredibly difficult aren’t really that bad…. I have been reviewing technology challenges for “exascale” computing and ran across an interesting comment in the 2008 “Technology Challenges in Achieving Exascale Systems” report. In Section 5.8 “Application Assessments”, Figure 5.16 on page 82 places “Ordered Summation” in the… read more