Multi-Core Software

The Foundations for Scalable Multi-Core Software in Intel® Threading Building Blocks

INTRODUCTION

Performance-oriented developers now face the daunting task of threading their applications. Introducing parallelism into an application is a large investment. It is therefore imperative to implement a scalable solution, one that continues to increase performance, as the number of available cores and threads increases.

Intel® TBB is a C++ template library that is designed to assist developers in porting their applications to multi-core platforms. The TBB library provides generic parallel algorithms [18] and concurrent containers [19] that enable users to write parallel programs without directly creating and managing threads. These algorithms are tested and tuned for the current generation of multi-core processors, and they are designed to scale as the core count continues to increase.

To provide efficient performance today and continued scalability tomorrow, the library is designed to support fine-grain parallelism through tasks. Tasks are user-level objects that are scheduled for execution by the TBB task scheduler. The task scheduler maintains a pool of native threads and a set of per-thread ready pools of tasks. At initialization, the TBB scheduler creates an appropriate number of threads in the pool (by default, 1 per hardware thread) and maintains the ready pools using a randomized work-stealing algorithm [2, 3].

In this paper, we describe the design of the TBB task scheduler and several scheduling optimizations users can keep in mind while coding their applications. In the Results section, we explore the scalability of TBB applications and highlight the impact of these scheduling optimizations on performance.

The task scheduler is complemented by the Intel TBB scalable memory allocator. In this paper, we provide an overview of its design and look at the tradeoffs. We compare its performance to several other commercial and non-commercial allocators.

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