Rock (processor)
| Company type | Microprocessor project |
|---|---|
| Industry | Semiconductor |
| Founded | 2005 |
| Founder | Sun Microsystems |
| Defunct | 2010 |
| Fate | Discontinued after Oracle acquisition of Sun Microsystems |
| Products | Multicore, multithreaded SPARC microprocessor |
| Parent | Sun Microsystems |
Rock (also referred to as ROCK) was a multicore, multithreaded SPARC microprocessor developed by Sun Microsystems but discontinued in 2010. This chip was separate from the SPARC T-Series (CoolThreads/Niagara) processors.
Unlike the Niagara family, Rock aimed to deliver superior per-thread performance and enhanced floating-point capabilities, along with better symmetric multiprocessing (SMP) scalability. Its design targeted demanding data-intensive applications such as backend database servers and floating-point-heavy high-performance computing, whereas Niagara processors were optimized for network-oriented workloads like web servers.
Processor core
The Rock CPU implements the 64-bit SPARC V9 instruction set architecture along with the VIS 3.0 SIMD multimedia extension. Each processor contains 16 cores, with each core capable of handling two concurrent threads, resulting in a total of 32 threads per chip. Servers utilizing Rock processors employ FB-DIMMs to improve memory reliability, throughput, and capacity. Fabricated using a 65 nm process technology, Rock operates at a clock speed of 2.3 GHz and has a peak power consumption near 250 watts.
Core cluster
The 16 cores are grouped into four core clusters. Within each cluster, cores share a 32 KB instruction cache, two separate 32 KB data caches, and a pair of floating point units. This architecture was crafted by Sun to efficiently support server workloads that typically exhibit high reuse of instructions and data but relatively low floating-point usage. By sharing these resources among four cores, the design achieves reductions in chip area and power draw with minimal impact on performance.
Unconventional features
In 2005, Sun introduced hardware scout, a mechanism that leverages unused processor resources to perform prefetching during cache miss events.
In March 2006, Marc Tremblay, Sun’s Vice President and Chief Architect for Scalable Systems, delivered a presentation covering thread-level parallelism, hardware scouting, and speculative multithreading—key technologies planned for integration into Rock.
By August 2007, Sun announced that Rock would be the first commercially available processor to incorporate transactional memory. This innovation introduced two new instructions (chkpt and commit) along with a status register (cps) to facilitate transaction management. Although transactional memory support was best-effort—transactions could abort due to conflicts such as data races, TLB misses, interrupts, or complex instructions—this feature promised significant benefits for synchronization-heavy code sections.
At the February 2008 ISSCC, Tremblay revealed the concept of "out-of-order retirement," replacing the conventional instruction window with a smaller deferred queue to enhance execution efficiency.
In April 2008, Sun engineers demonstrated the transactional memory interface at Transact 2008 and announced plans to publicly release the Adaptive Transactional Memory Test Platform simulator.
Server platforms
Rock was intended for use in Sun’s planned "Supernova" server lineup. The server platform specifications were documented in detail within the OpenSolaris Architecture Review case FWARC/2008/761.
Physical resources
The Physical Resource Inventory (PRI) specification outlined in ARC 2008/761 indicated that Supernova platforms would incorporate IEEE 1275 OpenFirmware support, platform virtualization through Logical Domains (LDOMs), an autonomous system controller (SC), and Fault Management Architecture (FMA) Domain Services. The FMA capabilities were further extended in FWARC/2008/455 to provide robust diagnostics for PCI fabric errors occurring within root domains.
Input/output
The ARC 2008/761 specification intended to incorporate support for PCI Express (PCIe) hot-plug slots alongside a bridging mechanism to interface with legacy PCI eXtended (PCI-X) technology.
Expandability
Supernova server configurations differed in their I/O capabilities: "Bronze" models accommodated PCIe slots numbered 0 through 5; "Silver" versions supported I/O boards 0 and 1, each equipped with PCIe slots 0 to 7; "Platinum" models enabled boards 0 to 3, each with slots 0 to 7; "Silver-II" servers offered PCIe slots ranging from 00 to 19; and "Platinum-II" systems supported boards 0 through 7, each containing slots numbered 0 to 3.
Systems
- AT7180 ("Bronze-II")
The SPARC Enterprise AT7180 featured a single CPU socket and could handle up to 32 hardware threads.
- AT7280 ("Bronze-II")
This dual-socket SPARC Enterprise AT7280 model supported a maximum of 64 hardware threads.
- AT7480 ("Silver-II")
The SPARC Enterprise AT7480 was designed with four sockets, supporting up to 128 hardware threads. It utilized PCI Express architecture and employed Open Boot firmware.
- AT7880 ("Platinum-II")
An eight-socket system, the SPARC Enterprise AT7880 supported as many as 256 hardware threads. It incorporated PCI Express bus architecture alongside Open Boot firmware and included eight CPU boards, each equipped with a Sun Neptune multithreaded 10 Gigabit Ethernet processor.
Product history
In February 2005, Sun Microsystems' CEO Scott McNealy announced that the Rock chip tape-out was progressing on schedule for that year; however, the release was postponed until January 2007. By April 2007, CEO Jonathan I. Schwartz introduced the BGA-packaged Rock chip, named UltraSPARC RK, which was capable of addressing up to 256 terabytes of virtual memory under Solaris. In May, Sun confirmed that the Rock chip had successfully booted Solaris.
Sun disclosed in August 2007 that Rock's architecture incorporated transactional memory; nonetheless, its intricate and distinctive design delayed its launch until 2008 or possibly 2009. During the Sun Labs Open House in 2008, Mark Moir presented on Rock’s transactional memory and thread scouting techniques, emphasizing how massive multithreading could address computational challenges. Later that September, the OpenSolaris initiative began integrating support for the Rock-based SuperNova platform.
By January 2009, CEO Jonathan Schwartz reiterated that Rock's release remained on schedule for that year. In March, Sun researchers showcased preliminary findings related to commercial hardware transactional memory implementation within Rock at the ASPLOS '09 conference, underlining its importance in advancing multicore processor technology.
Cancellation
On April 20, 2009, Sun and Oracle Corporation announced a definitive agreement for Oracle’s acquisition of Sun Microsystems. A blog post from Sun dated June 12 revealed plans for a technical presentation under NDA regarding ROCK at the Hamburg OpenSolaris Users Group Meeting scheduled for July 14, 2009.
However, on June 15, 2009, the New York Times cited unnamed sources indicating that the Rock project had been terminated; Sun did not provide an official statement. Two days afterward, EE Times reported that Sun’s absence from Hot Chips 21 submissions concerning Rock intensified speculation about its cancellation. On June 24, a presentation titled "Speculative Threading & Parallelization" discussed "A Novel Pipeline Architecture Implemented in Sun's ROCK Processor" at The 36th International Symposium on Computer Architecture.
By August 6, 2009, all support for Rock had been withdrawn from the OpenSolaris Project. On August 13, a paper entitled "NZTM: Nonblocking Zero-indirection Transactional Memory" evaluated performance metrics on the anticipated Rock processor at the 21st ACM Symposium on Parallelism in Algorithms and Architectures. Then on September 11, The Register reported that Rock was excluded from the SPARC processor roadmap shared with customers and partners. Research papers released in September and October further explored transactional memory and debugging tools associated with Rock’s design.
Oracle completed its acquisition of Sun on January 27, 2010. In April of that year, multiple papers were presented at the ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), including works titled "Simplifying Concurrent Algorithms by Exploiting Hardware Transactional Memory" and "TLRW: Return of the Read-Write Lock," reflecting ongoing investigations linked to Rock technology.
On May 12, 2010, Reuters reported Oracle CEO Larry Ellison confirmed the termination of the Rock project following the acquisition. He cited its subpar performance and excessive power consumption: "It was incredibly slow and it consumed vast amounts of energy," Ellison stated. "It generated so much heat that approximately a foot of cooling fans was necessary... Continuing that project was simply irrational."