On Performance Debugging of Unnecessary Lock Contentions on Multicore Processors: A Replay-based Approach

Locks have been widely used as an effective synchronization mechanism among processes and threads. However, we observe that a large number of false inter-thread dependencies (i.e., unnecessary lock contentions) exist during the program execution on multicore processors, thereby incurring significant performance overhead. This paper presents a performance debugging framework, PERFPLAY, to facilitate a comprehensive and in-depth understanding of the performance impact of unnecessary lock contentions. The core technique of our debugging framework is trace replay. Specifically, PERFPLAY records the program execution trace, on the basis of which the unnecessary lock contentions can be identified through trace analysis. We then propose a novel technique of trace transformation to transform these identified unnecessary lock contentions in the original trace into the correct pattern as a new trace free of unnecessary lock contentions. Through replaying both traces, PERFPLAY can quantify the performance impact of unnecessary lock contentions. To demonstrate the effectiveness of our debugging framework, we study five real-world programs and PARSEC benchmarks. Our experimental results demonstrate the significant performance overhead of unnecessary lock contentions, and the effectiveness of PERFPLAY in identifying the performance critical unnecessary lock contentions in real applications.Comment: 18 pages, 19 figures, 3 table

Mobilizing Personalized Federated Learning in Infrastructure-Less and Heterogeneous Environments via Random Walk Stochastic ADMM

This paper explores the challenges of implementing Federated Learning (FL) in practical scenarios featuring isolated nodes with data heterogeneity, which can only be connected to the server through wireless links in an infrastructure-less environment. To overcome these challenges, we propose a novel mobilizing personalized FL approach, which aims to facilitate mobility and resilience. Specifically, we develop a novel optimization algorithm called Random Walk Stochastic Alternating Direction Method of Multipliers (RWSADMM). RWSADMM capitalizes on the server's random movement toward clients and formulates local proximity among their adjacent clients based on hard inequality constraints rather than requiring consensus updates or introducing bias via regularization methods. To mitigate the computational burden on the clients, an efficient stochastic solver of the approximated optimization problem is designed in RWSADMM, which provably converges to the stationary point almost surely in expectation. Our theoretical and empirical results demonstrate the provable fast convergence and substantial accuracy improvements achieved by RWSADMM compared to baseline methods, along with its benefits of reduced communication costs and enhanced scalability.Comment: 28 pages, 7 figures, 3 tables, 1 algorithm. Proof details are provided in the main body of the pape

Antagonistic actions of boron against inhibitory effects of aluminum toxicity on growth, CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase, and photosynthetic electron transport probed by the JIP-test, of Citrus grandis seedlings

<p>Abstract</p> <p>Background</p> <p>Little information is available on the amelioration of boron (B) on aluminum (Al)-induced photosynthesis inhibition. Sour pummelo (<it>Citrus grandis</it>) seedlings were irrigated for 18 weeks with nutrient solution containing 4 B levels (2.5, 10, 25 and 50 μM H₃BO₃) × 2 Al levels (0 and 1.2 mM AlCl₃·6H₂O). The objectives of this study were to determine how B alleviates Al-induced growth inhibition and to test the hypothesis that Al-induced photosynthesis inhibition can be alleviated by B <it>via </it>preventing Al from getting into shoots.</p> <p>Results</p> <p>B had little effect on plant growth, root, stem and leaf Al, leaf chlorophyll (Chl), CO₂assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Chl a fluorescence (OJIP) transient and related parameters without Al stress except that root, stem and leaf B increased with increasing B supply and that 50 μM B decreased slightly root dry weight. Al-treated roots, stems and leaves displayed a higher or similar B. B did not affect root Al under Al stress, but decreased stem and leaf Al level. Shoot growth is more sensitive to Al stress than root growth, CO₂assimilation, Chl, Rubisco, OJIP transient and most related parameters. Al-treated leaves showed decreased CO₂assimilation, but increased or similar intercellular CO₂concentration. Both initial and total Rubisco activity in Al-treated leaves decreased to a lesser extent than CO₂assimilation. Al decreased maximum quantum yield of primary photochemistry and total performance index, but increased minimum fluorescence, K-band, relative variable fluorescence at J- and I-steps. B could alleviate Al-induced increase or decrease for all these parameters. Generally speaking, the order of B effectiveness was 25 μM > 10 μM ≥ 50 μM (excess B) > 2.5 μM.</p> <p>Conclusion</p> <p>We propose that Al-induced photosynthesis inhibition was mainly caused by impaired photosynthetic electron transport chain, which may be associated with growth inhibition. B-induced amelioration of root inhibition was probably caused by B-induced changes in Al speciation and/or sub-cellular compartmentation. However, B-induced amelioration of shoot and photosynthesis inhibition and photoinhibitory damage occurring at both donor and acceptor sides of photosystem II could be due to less Al accumulation in shoots.</p

The research progress on the mechanism of adenosine A1 receptor-mediated calcitonin gene-related peptide to relieve migraine

Currently, the pathogenesis of migraine is unclear. The trigeminal vascular reflex theory is the dominant pathogenesis theory, and its core parts are neurogenic inflammation and pain sensitisation. Calcitonin gene related peptide (CGRP) is the most powerful vasodilating peptide in brain circulation. It is also a marker of trigeminal nerve microvascular activation that plays a synergistic role in the pathogenesis of migraine. Adenosine A1 receptor (A1R) can inhibit the release of CGRP in the trigeminal nerve vascular system to alleviate migraine by mediating adenosine. This review summarises the progress of research on the alleviation of migraine by using A1R-mediated CGRP

Effect of bandage lens after pterygium excision combined with corneal stem cell transplantation

AIM: To evaluate the clinical effect of wearing bandage lens after pterygium excision combined with corneal stem cell transplantation. METHODS: This study was a prospective analysis. Totally 110 cases 110 eyes of pterygium excision combined with corneal stem cell transplantation admitted to our hospital from August 2015 to February 2018 were randomly divided into control group and observation group with 55 cases in each group. Patients in observation group wore bandage lens after operation. Visual analogue scale(VAS)was used to evaluated the pain 1, 3d and 1wk after operation. Fluorescein staining(FL)was used to evaluate the corneal epithelial healing and the incidence of complications. RESULTS: The VAS score and corneal epithelial healing score of the observation group were significantly lower than those of the control group at 1, 3d and 1wk after operation(PP>0.05). CONCLUSION: It is safe and effective to wear bandage lens after pterygium excision combined with corneal stem cell transplantation. It can relieve pain and promote epithelial healing after pterygium operation

Background-free in-vivo imaging of Vitamin C using time-gateable responsive probe

Sensitive optical imaging of active biomolecules in the living organism requires both a molecular probe specifically responsive to the target and a high-contrast approach to remove the background interference from autofluorescence and light scatterings. Here, a responsive probe for ascorbic acid (vitamin C) has been developed by conjugating two nitroxide radicals with a long-lived luminescent europium complex. The nitroxide radical withholds the probe on its "off" state (barely luminescent), until the presence of vitamin C will switch on the probe by forming its hydroxylamine derivative. The probe showed a linear response to vitamin C concentration with a detection limit of 9.1 nM, two orders of magnitude lower than that achieved using electrochemical methods. Time-gated luminescence microscopy (TGLM) method has further enabled real-time, specific and background-free monitoring of cellular uptake or endogenous production of vitamin C, and mapping of vitamin C in living Daphnia magna. This work suggests a rational design of lanthanide complexes for background-free small animal imaging of biologically functional molecules