We had discussed the six editions of the authoritative text on computer architecture. Eight years after the 6th edition, we have the 7th edition published in October 2025. A quick scan of the table of content seems to show few new topics. There is no large increase of page counts, only about 40 pages. A third author is added. The famous processor performance chart is extended by a few years, but only to 2022 and the performance increases from 2015 is revised up to 9% a year (from 3.5%). The top processor at 2017 is Intel Core i7 4.2GHz with performance score of 49,935, and at 2022 Intel Xeon E-2388G 3.2GHz with score 88,833. Note the performance increase of 80% while the clock speed actually goes down (though the boost speed is a little higher). The Moore's law seems to continue but performance increase has been significantly curtailed since 2004 when the Dennard's scaling law ended.
What has been going on in this eight years? The emergence of AI, represented by ChatGPT that made debut in 2022 is the most significant. There is a mad dash to adopt AI in every industries and in everyday life. And datacenters that support AI are being built in a such scale that causes shortage in chips and propels NVidia to one of the most valuable companies. The vulnerability of computer architecture to malicious attack such as Meltdown and Spectre stunned computer architects. The bedrock of the modern processor techniques of cache memory and speculative execution can be exploited. The security issues are addressed in the new edition: side-channel attacks on the memory system and speculative and multithreading execution unit. With this the authors admonish the lack of adequate tools to address the security issues in processor design.
The chapter on warehouse-scale computing debuted in the fifth edition (2011) (as the book cover starts to show cloud). The discussion always seems to be me have been a little weak. That situation has largely been remedied in this new edition. But curiously, the concept of request-level parallelism, coined when the WSC was first introduced is merged into thread-level parallelism, as the cores become more numerous.
And the chapter on domain-specific architecture debuted in the sixth edition (2017) has shown significant improvements.
Despite of many clever architectural innovation, the quantitative aspect of the computer design still seems naive. The mathematical tools are so elementary (as in only elementary school arithmetic). Perhaps we need to introduce more sophisticated tools or language to model computer architecture more precisely. Queuing theory was introduced briefly related to storage system.
The realization of the similarities between vector processors and GPUs is significant. It bridges the two seemingly disparate concepts and allows a more uniform discussion, using the traditional language of computer architecture to discuss the GPUs which have evolved their own terminologies, unfamiliar to the outsiders. As the GPUs break through the original 3D graphics accelerator to more general high-performance computing, that is especially suited for the AI processing. And the GPUs have introduced low resolution float number computing unit particularly targeted the AI applications.
