Software automatic tuning is a technology paradigm enabling software adaptation to a variety of computational conditions. Originating from the stream of research works on highperformance computing, it is considered to be the most promising approach to the required performance advancements on the next generation supercomputing platforms. Also, as its effectiveness is widely recognized, its scope is expanding from scientific and engineering computations to general purpose computations.

This book is a fruit of international collaboration developed in iWAPT workshop series, where iWAPT stands for InternationalWorkshop on Automatic Performance Tuning. The first workshop (iWAPT 2006) has been held in the University of Tokyo on September 12, 2006. It was a 1-day workshop with two invited presentations from USA and four invited presentations from Japan. iWAPT 2007 was a 2-day workshop with three invited presentations, seven refereed oral presentations, and eight poster presentations, held at the University of Tokyo. In 2008, iWAPT was held in conjunction with IEEE Cluster 2008 at Tsukuba, with two invited presentations and seven refereed oral presentations. iWAPT 2009 was a 2-day workshop with two invited presentations seven refereed oral presentations and four poster presentations, held at the University of Tokyo. iWAPT 2010 will be held in conjunction with VECPAR at Berkeley, CA, USA iWAPT is now lead by International Steering Committee, where five members are from Japan, four from USA, and one from Europe (see http://www.iwapt.org).

This book consists of 20 chapters that encompass almost all the areas of automatic tuning research:matrix kernels, FFT, matrix decompositions, iterative solvers, numerical library, scientific computing, GPGPU, parallel processing, autotuning framework, mathematical methods of autotuning, programming languages, and compiler technologies. The first chapter is an introduction to software automatic tuning, written by the editors. Six chapters are invited papers. Two of them are written by invited speakers of iWAPT workshops, and four of them are by members of organizing committee of iWAPT workshops. Thirteen chapters are peerreviewed contributed papers. Six come from iWAPT 2009, two from iWAPT 2007, and the other five papers are newly submitted for this publication. We arrange the chapters in the order of topics, rather than in the order of origins.