Towards consistency oblivious programming

15th International Conference, OPODIS 2011, Toulouse, France, December 13-16, 2011. ProceedingsIt is well known that guaranteeing program consistency when accessing shared data comes at the price of degraded performance and scalability. This paper initiates the investigation of consistency oblivious programming (COP). In COP, sections of concurrent code that meet certain criteria are executed without checking for consistency. However, checkpoints are added before any shared data modification to verify the algorithm was on the right track, and if not, it is re-executed in a more conservative and expensive consistent way. We show empirically that the COP approach can enhance a software transactional memory (STM) framework to deliver more efficient concurrent data structures from serial source code. In some cases the COP code delivers performance comparable to that of more complex fine-grained structures

Interrupting snapshots and the Java[superscript TM] size method

The Java[superscript TM] developers kit requires a size() operation for all objects, tracking the number of elements in the object. Unfortunately, the best known solution, available in the Java concurrency package, has a blocking concurrent implementation that does not scale. This paper presents a highly scalable wait-free implementation of a concurrent size() operation based on a new lock-free interrupting snapshots algorithm. The key idea behind the new algorithm is to allow snapshot scan methods to interrupt each other until they agree on a shared linearization point with respect to update methods. This contrasts sharply with past approaches to the classical atomic snapshot problem, that have had threads coordinate the collecting of a shared global view. As we show empirically, the new algorithm scales well, significantly outperforming existing implementations.European Union (Project VELOX Grant FP7-ICT-2007-1

Amalgamated Lock-Elision

International audienceHardware lock-elision (HLE) introduces concurrency into legacy lock-based code by optimistically executing critical sections in a fast-path as hardware transactions. Its main limitation is that in case of repeated aborts, it reverts to a fallback-path that acquires a serial lock. This fallback-path lacks hardware- software concurrency, because all fast-path hardware transactions abort and wait for the completion of the fallback. Software lock elision has no such limitation, but the overheads incurred are simply too high.We propose amalgamated lock-elision (ALE), a novel lock-elision algorithm that provides hardware-software concurrency and efficiency: the fallback-path executes concurrently with fast-path hardware transactions, while the common-path fast-path reads incur no overheads and proceed without any instrumentation. The key idea in ALE is to use a sequence of fine-grained locks in the fallback-path to detect conflicts with the fast-path, and at the same time reduce the costs of these locks by executing the fallback-path as a series segments, where each segment is a dynamic length short hardware transaction.We implemented ALE into GCC and tested the new system on Intel Haswell 16-way chip that provides hardware transactions. We benchmarked linked-lists, hash-tables and red-black trees, as well as converting KyotoCacheDB to use ALE in GCC, and all show that ALE significantly outperforms HLE

A Bounded First-In, First-Enabled Solution to the l-Exclusion Problem

This paper presents a solution to the first-come, first-enabled `-exclusion problem of [?]. Unlike the solution in [?], this solution does not use powerful read-modify-write synchronization primitives, and requires only bounded shared memory. Use of the concurrent timestamp system of [?] is key in solving the problem within bounded shared memory. Categories and Subject Descriptors: D.4.1 [Operating Systems]: Process Management---Mutua

Evaluating the Epidemiology and Morbidity Burden Associated with Human Papillomavirus in Israel: Accounting for CIN1 and Genital Warts in Addition to CIN2/3 and Cervical Cancer

Background:Background: Human papillomavirus (HPV) infection is mostly associated with cervical cancer (CC). However, it can cause other illnesses as well, all of which impact on people's wellbeing and consume healthcare resources. Measures for prevention or early detection of these conditions differ in their effectiveness and cost. An informative evaluation of the projected benefit of these measures depends on understanding the current unmet need, not only limited to CC. Abstract: Objective:Objective: To evaluate the burden of HPV-related conditions in Israel, including CC, cervical precancerous lesions and genital warts. Abstract: Methods:Methods: A retrospective database analysis was conducted for the second largest health management organization (HMO) in Israel, covering approximately 1.8 million people. Records were drawn following a search for key words indicative of related diagnoses, lab results, medications, or procedures for the time period of 2006-2008. Prevalence, incidence and resource utilization were analysed. Findings were extrapolated to the whole Israeli population using age and gender incidence rates. Abstract: Results:Results: Incidence of CC was found to be 5 per 100 000 females. Incidences of cervical intraepithelial neoplasia (CIN) grades 1, 2 and 3 were 74, 27 and 36 per 100 000 females, respectively. Incidence of genital warts was 239 and 185 per 100 000 for men and women, respectively. The overall annual economic burden was calculated to be $US48 838 058 (year 2010 values). Abstract: Conclusions:Conclusions: HPV poses a significant burden in terms of health (clinical and quality of life) and in monetary terms, even for conditions that are sometimes regarded as benign, such as CIN1 or genital warts. Current findings should be used for proper evaluation of measures to reduce HPV-related morbidity and mortality, such as regular screening and vaccination.Cervical-cancer, Cervical-intraepithelial-neoplasia, Cost-of-illness, Genital-warts, Human-papillomavirus-infections.