Merging and Prioritizing Optimization in Block I/O Scheduling of Disk Storage

I/O merging optimization at the block I/O layer of disk storage is widely adopted to reduce I/O response time. But it may result in certain overhead of merging judgment in the case of a large number of concurrent I/O requests accessing disk storage, and place negative effects on the response of small requests. This paper proposes a divide and conquer scheduling scheme at the block layer of I/O stack, to satisfy a large number of concurrent I/O requests with less I/O response time and ensure the fairness of each request response by decreasing the average I/O latency. First, we propose a horizontal visibility graph-based approach to cluster relevant block requests, according to their offsets (i.e., logic block numbers). Next, it carries out the optimization operation of merging consecutive block I/O requests within each cluster, as only these requests in the same cluster are most likely to be issued by a specific application. Then, we have introduced the functionality of merging judgment when performing merging optimization to effectively guarantee the average I/O response time. After that, the merged requests in the queue will be reordered on the basis of their priorities, to purposely cut down the average I/O response time. Finally, the prioritized requests are supposed to be delivered to the disk storage, for being serviced. Through a series of experiments, we show that compared to the benchmark, the newly proposed scheme can not only cut down the I/O response time by more than 18.2%, but also decrease the average I/O response time up to 71.7%.

Phisycal And Chemical Properties And Nutrient Content (N, P, K, Mg, B, Cu And Zn ) In Oil Palm Leaf In Various Of Age After Compacting

Planting of oil palm in peatland has been limited by soil physical, chemical properties, and hydrology, that`s way needed improvement on those matters to increase the productivity of peat and oil palm in peat soil by compacting. The purpose of this compacting is to improve the soil's physical, chemical properties, and soil moisture. A sampling of soil, water, and leaf were done in consecutive block 5,4,3,2,1,0 year after compacting and of planting done 4 years 10 months, 3 years 9 months, 2 years 9 months, 1 year 10 months, 11 months and 2 months, control used in this trial are origin condition (forest). Increasing bulk density was found at compacting block with 30 cm depth from the surface with the lower in 2 years after compacting at 0.09 g/cm3 and highest 4 years after compacting 0.4 g/cm3. In-depth of 60 cm from surface was found no increasing the bulk density 3 years after compacting 0.0 g/cm3 and the highest on 5 years after compacting 0.3 g/cm3 compared to forest. Decreasing on permeability in-depth 30 cm at 4 years after compacting 7.47 cm/jam and close to forest permeability 51.11 cm/hour is 2 years 43.6 cm/hour. As represent rise capillary consistently water content ≥ 80% achieved at depth 20 cm of surfaces on all block. Compaction doesn't regard pH, C organic, basa's saturation, capacity exchange cation. On depth 30 cm P-total lower on s without compaction at 599.6 ppm and above 871.6 ppm on 5 yr than forest 585 ppm. P available most low 58.1 ppm happens on 4 yr afters is compacted and p available forest 53.9 ppm. Nutrient content B, Cu and Zn at soil not influenced by compaction. Fosfor (P) in water increases with added years after compaction lower at 39.1 mg/L in the block without compaction compare of forest that 40.8 mg/L. Leaf nutrient rate on compacted block on optimum until excess where N (2. 69 – 3.15 %) , P (0. 170 – 0.209 %) , K( 0. 952 – 1.11%) , Mg ( 0. 377 – 0.497%) , except on block without compacting K (0. 830 %) and Mg (0. 190%) at deficiency and 0 years afters compaction Mg leaf on level deficiency 0. 230%. Nutrient content of B, Cu and Zn at various level and not influenced by compacting.