32,606 research outputs found
Efficient Logging in Non-Volatile Memory by Exploiting Coherency Protocols
Non-volatile memory (NVM) technologies such as PCM, ReRAM and STT-RAM allow
processors to directly write values to persistent storage at speeds that are
significantly faster than previous durable media such as hard drives or SSDs.
Many applications of NVM are constructed on a logging subsystem, which enables
operations to appear to execute atomically and facilitates recovery from
failures. Writes to NVM, however, pass through a processor's memory system,
which can delay and reorder them and can impair the correctness and cost of
logging algorithms.
Reordering arises because of out-of-order execution in a CPU and the
inter-processor cache coherence protocol. By carefully considering the
properties of these reorderings, this paper develops a logging protocol that
requires only one round trip to non-volatile memory while avoiding expensive
computations. We show how to extend the logging protocol to building a
persistent set (hash map) that also requires only a single round trip to
non-volatile memory for insertion, updating, or deletion
webXice: an Infrastructure for Information Commerce on the WWW
Systems for information commerce on the WWW have to support flexible business models if they should be able to cover a wide range of requirements imposed by the different types of information businesses. This leads to non-trivial functional and security requirements both on the provider and consumer side, for which we introduce an architecture and a system implementation, webXice. We focus on the question, how participants with minimal technological requisites, i.e. solely standard Web browsers available, can be technologically enabled to articipate in the information commerce at a system level, while not sacrificing the functionality and security required by an autonomous participant in an information commerce scenario. In particular, we propose an implementation strategy to efficiently support persistent message logging for light-weight clients, that enables clients to collect and manage non-reputiable messages as proofs. We believe that the capability to support minimal system platforms is a necessary precondition for the wide-spread use of any information commerce infrastructure
Improving the Performance and Endurance of Persistent Memory with Loose-Ordering Consistency
Persistent memory provides high-performance data persistence at main memory.
Memory writes need to be performed in strict order to satisfy storage
consistency requirements and enable correct recovery from system crashes.
Unfortunately, adhering to such a strict order significantly degrades system
performance and persistent memory endurance. This paper introduces a new
mechanism, Loose-Ordering Consistency (LOC), that satisfies the ordering
requirements at significantly lower performance and endurance loss. LOC
consists of two key techniques. First, Eager Commit eliminates the need to
perform a persistent commit record write within a transaction. We do so by
ensuring that we can determine the status of all committed transactions during
recovery by storing necessary metadata information statically with blocks of
data written to memory. Second, Speculative Persistence relaxes the write
ordering between transactions by allowing writes to be speculatively written to
persistent memory. A speculative write is made visible to software only after
its associated transaction commits. To enable this, our mechanism supports the
tracking of committed transaction ID and multi-versioning in the CPU cache. Our
evaluations show that LOC reduces the average performance overhead of memory
persistence from 66.9% to 34.9% and the memory write traffic overhead from
17.1% to 3.4% on a variety of workloads.Comment: This paper has been accepted by IEEE Transactions on Parallel and
Distributed System
Multi-State Logging Freeze Detection Passive RFID Tags
In this work the design and measurement of a passive UHF RFID smart tag suitable for monitoring and recording critical temperature violations in cold chain management are presented. The tag uses moving parts to detect and log different temperate states without the requirement for transceivers, memory and batteries. A simple mechanical method is proposed whereby a moving metallic plate is trapped in one of 4 possible positions by specific environmental temperatures whereby inducing a permanent state based change in the passive RFID tag response. The latched product critical temperature violations can be monitored via the read power required to turn on the tag transponder chip which differs in each state
ElasTraS: An Elastic Transactional Data Store in the Cloud
Over the last couple of years, "Cloud Computing" or "Elastic Computing" has
emerged as a compelling and successful paradigm for internet scale computing.
One of the major contributing factors to this success is the elasticity of
resources. In spite of the elasticity provided by the infrastructure and the
scalable design of the applications, the elephant (or the underlying database),
which drives most of these web-based applications, is not very elastic and
scalable, and hence limits scalability. In this paper, we propose ElasTraS
which addresses this issue of scalability and elasticity of the data store in a
cloud computing environment to leverage from the elastic nature of the
underlying infrastructure, while providing scalable transactional data access.
This paper aims at providing the design of a system in progress, highlighting
the major design choices, analyzing the different guarantees provided by the
system, and identifying several important challenges for the research community
striving for computing in the cloud.Comment: 5 Pages, In Proc. of USENIX HotCloud 200
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