What is speculative execution computer?

What is speculative execution computer?

Speculative execution is an optimization technique in which a processor (CPU) performs a series of tasks before it is prompted to, in order to have the information ready if it is required at any point. It will then begin speculatively executing them before it knows which of the two branches it will actually be using.

Why is speculative execution good?

Along with multiple branch prediction (used to predict the instructions most likely to be needed in the near future) and dataflow analysis (used to align instructions for optimal execution, as opposed to executing them in the order they came in), speculative execution delivered a dramatic performance improvement over …

What is a speculative execution vulnerability?

Spectre is a class of security vulnerabilities that affects modern microprocessors that perform branch prediction and other forms of speculation. On most processors, the speculative execution resulting from a branch misprediction may leave observable side effects that may reveal private data to attackers.

What is the purpose of speculative execution Why is it usually restricted to the map phase?

The goal of speculative execution is to reduce job’s response time. But on a busy cluster it may affect the overall throughput of data and wastage of cluster resources.

How speculative execution can help the system speed up?

Speculative execution is a technique used by modern CPUs to speed up performance. The CPU may execute certain tasks ahead of time, “speculating” that they will be needed. If the tasks are required, a speed-up is achieved, because the work is already complete.

What is speculative execution delaying execution?

In Hadoop, MapReduce breaks jobs into tasks and these tasks run parallel rather than sequential, thus reduces overall execution time. This model of execution is sensitive to slow tasks (even if they are few in numbers) as they slow down the overall execution of a job. This is called speculative execution in Hadoop.

What is speculative processing?

Speculation (also known as speculative loading ), is a process implemented in Explicitly Parallel Instruction Computing ( EPIC ) processors and their compiler s to reduce processor-memory exchanging bottlenecks or latency by putting all the data into memory in advance of an actual load instruction.

What is speculative execution side channel vulnerabilities?

This vulnerability is known as Speculative Execution Side-Channel Vulnerabilities (Meltdown and Spectre) which they refer to a hardware bug in the CPU which also affects a wide variety of Operating Systems including Windows (Server & Client), Android, Chrome, iOS and MacOS.

Why speculative execution is important in Hadoop environment in particular?

Hadoop MapReduce Speculative execution is beneficial in some cases because in a Hadoop cluster with 100s of nodes, problems like hardware failure or network congestion are common and running parallel or duplicate task would be better since we won’t be waiting for the task in the problem to complete.

Why is speculative execution important in Hadoop?

The main goal of the speculative execution is to reduce job execution time. But this will come at the cost of the Hadoop cluster efficiency. On a busy Hadoop cluster, this may reduce the overall throughput because the redundant tasks are being executed in order to reduce the execution time for the single job.

What is speculative execution explain with the help of an example?

Speculative execution is a technique used by modern CPUs to speed up performance. The CPU may execute certain tasks ahead of time, “speculating” that they will be needed. For example, the Meltdown security vulnerability affects some Intel CPUs due to a flaw in their speculative execution.

Does ARM have speculative execution?

On impacted processors, Arm says that while computing operations in advance part of the speculative execution process, when there’s a change in the Arm CPU’s instruction control flow, the CPU reacts by executing instructions found linearly in its memory, past the change in the control flow — an unwanted scenario.

What is speculative execution and how does it work?

Speculative execution is a technique used to increase the performance of all modern microprocessors to one degree or another, including chips built or designed by AMD, ARM, IBM, and Intel. The modern CPU cores that don’t use speculative execution are all intended for ultra-low power environments or minimal processing tasks.

What are some common security flaws that target speculative execution?

Various security flaws like Spectre, Meltdown, Foreshadow, and MDS all targeted speculative execution a few years ago, typically on Intel CPUs. What Is Speculative Execution?

What is the difference between eager execution and speculative computation?

Speculative computation was a related earlier concept. Eager execution is a form of speculative execution where both sides of the conditional branch are executed; however, the results are committed only if the predicate is true.

When did the speculative execution vulnerabilities start?

Starting in 2017, a series of security vulnerabilities were found in the implementations of speculative execution on common processor architectures which effectively enabled an elevation of privileges . ^ a bInternational Business Machines Corporation. Research Division; Prabhakar Raghavan; Hadas Schachnai; Mira Yaniv (1998).