25,457 research outputs found
Telescope: Telemetry at Terabyte Scale
Data-hungry applications that require terabytes of memory have become
widespread in recent years. To meet the memory needs of these applications,
data centers are embracing tiered memory architectures with near and far memory
tiers. Precise, efficient, and timely identification of hot and cold data and
their placement in appropriate tiers is critical for performance in such
systems. Unfortunately, the existing state-of-the-art telemetry techniques for
hot and cold data detection are ineffective at the terabyte scale.
We propose Telescope, a novel technique that profiles different levels of the
application's page table tree for fast and efficient identification of hot and
cold data. Telescope is based on the observation that, for a memory- and
TLB-intensive workload, higher levels of a page table tree are also frequently
accessed during a hardware page table walk. Hence, the hotness of the higher
levels of the page table tree essentially captures the hotness of its subtrees
or address space sub-regions at a coarser granularity. We exploit this insight
to quickly converge on even a few megabytes of hot data and efficiently
identify several gigabytes of cold data in terabyte-scale applications.
Importantly, such a technique can seamlessly scale to petabyte-scale
applications.
Telescope's telemetry achieves 90%+ precision and recall at just 0.009%
single CPU utilization for microbenchmarks with a 5 TB memory footprint. Memory
tiering based on Telescope results in 5.6% to 34% throughput improvement for
real-world benchmarks with a 1-2 TB memory footprint compared to other
state-of-the-art telemetry techniques
GPS analysis of a team competing at a national Under 18 field hockey tournament
The purpose of this study was to utilise global-positioning system (GPS) technology to quantify the running demands of national Under 18 field hockey players competing in a regional field hockey tournament. Ten male players (mean ± SD; age 17.2 ± 0.4 years; stature 178.1 ± 5.2 cm; body mass 78.8 ± 8.8 kg) wore GPS units while competing in six matches over seven days at the 2018 New Zealand national under 18 field hockey tournament. GPS enabled the measurement of total distance (TD), low-speed activity (LSA; 0 -14.9 km/hr), and high-speed running (HSR; ≥ 15 km/hr) distances. Differences in running demands (TD, LSA, HSR) between positions were assessed using effect size and percent difference ± 90% confidence intervals. Midfielders covered the most TD and LSA per game and strikers the most HSR during the 6 matches. There were “very large” differences between strikers and midfielders for TD and LSA, strikers and defenders for LSA and HSR, and defenders and midfielders for LSA. These results suggest that these playing positions are sufficiently different to warrant specialised position-specific conditioning training leading into a field hockey tournament
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