Rotational position optimization disk scheduling algorithms utilize seek distance versus rotational distance information implemented as rpo tables (arrays) which are stored in flashmemory within each disk drive. We consider a novel representation scheme for this information reducing the required flashmemory by a factor of more than thirty thereby reducing the manufacturing cost per drive. We present simulation results showing the throughput for conservative and aggressive versions of the scheme as well as comparative results with the standard production drives not using these results.

Pre-2018 CSE ID: CS2001-0679

Correlation functions for holonomic fields on the Poincare' disk are analyzed. The two point functions are shown to be expressible in terms of Painleve' functions of type VI.

The Linux kernel utilizes caches to speed up accesses to the high-usage objects that are normally stored on disks, such as data cache pages for files, inodes, and directory entries. These cache data types are implemented using separate chaining. In our experience, we found that some of the hash functions used in th circa 2000 Linux kernel can results, for certain access patterns, in very skewed data distributions over the chains. Better hash functions are desirable. In this paper, we analyze the data distribution and run-time efficiencies of a set of hash function for Linux inode and directory caches. Our analysis utilizes data traces from both an industry standard benchmark and two real world computing environments. Although some of the results were anticipated by Lever, who has carried out a similar study, we show that his results can be further improved.

Pre-2018 CSE ID: CS2001-0680