傅里叶的猫·2025-12-02 13:34Core Insights - The article discusses Google's TPU v7 interconnect architecture, focusing on the ratio of TPU to copper cables and optical modules, highlighting the technical aspects of the TPU design and its cooling solutions [1][6][7]. TPU Rack Interconnect Architecture - One of the notable features of TPU is its ability to achieve large-scale world size expansion through the ICI protocol, with a TPU Pod capable of accommodating up to 9216 Ironwood TPUs [2]. - Each TPU rack consists of 16 TPU trays and a varying number of host CPU trays, along with a top-of-rack switch and power units [2]. - The TPU tray contains a TPU board with four TPU chips, each equipped with multiple interfaces for interconnectivity [2]. Cooling Solutions - Google has adopted liquid cooling for TPU racks since the TPU v3 era, with a 1:1 ratio of TPU trays to host CPU trays in liquid-cooled racks, compared to a 2:1 ratio in air-cooled racks [6]. - The market anticipates that 2024 will be the "year of liquid cooling," as more ASIC servers begin to adopt this technology, indicating significant market growth potential [6]. Market Projections - In 2026, Google is expected to ship 2.5 million TPU v7 units, leading to a liquid cooling market space of approximately $2.8 to $3.2 billion [7]. - By 2027, shipments are projected to exceed 5 million units, with the value of liquid cooling per rack potentially increasing to $90,000 to $100,000, resulting in a market space of $7 to $8 billion [7]. Interconnect Design - The TPU v7 utilizes a 3D torus topology for interconnectivity, where each TPU connects to six neighboring nodes across three dimensions [8]. - Internal connections within the TPU tray use copper cables, while external connections utilize optical modules and OCS for inter-unit communication [9][12]. Optical Connectivity and Market Demand - A TPU Pod with 9216 TPUs will require approximately 11,520 copper cables and 13,824 optical modules, indicating a significant demand for optical components in the market [16]. - Google is projected to need around 15,000 OCS switches by 2026, with a market space for OCS estimated at $2.2 billion based on a price of $150,000 per switch [17][18].