The Linux Beacon--SGI Goes All the Way With Transitive Emulator

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Volume 2, Number 30 -- August 9, 2005

SGI Goes All the Way With Transitive Emulator

by Timothy Prickett Morgan

Back in May, server and workstation vendor Silicon Graphics became the first company to openly use the QuickTransit hardware virtualization product from a relatively unknown startup called Transitive to support Unix applications on a non-Unix platform. Specifically, SGI licensed the QuickTransit technology to allow Irix Unix applications to run on its Linux-Itanium line of Prism workstations. Last week, SGI went all the way, and has licensed the technology to allow Irix applications to run on its Altix line of Linux-Itanium servers.

Transitive launched QuickTransit last September and has been looking for makers of servers, workstations, and other computing platforms to embed that emulation layer in their products. QuickTransit is the brainchild of Alasdair Rawsthorne, a computer science professor at Manchester University in England and a processor designer who asked students to help him crack the software emulation problem. After five years of playing around, Transitive was formed in 2000 and after nearly five years of development and three rounds of venture capital totaling $24 million, the company is getting its first customers. SGI is now using QuickTransit to support Irix applications on its Prism workstations and Altix servers, and Apple plans to use a variant of QuickTransit, which is calls the "Rosetta" environment, to support PowerPC applications on its future X64-based Apple platforms. (Apple announced in May that it would over the next 18 months move from PowerPC to Intel X64 chips for its entire product line.)

The official QuickTransit product has three key parts: a front end where the binaries written for one platform (for instance, Irix applications running on MIPS servers) reside and a back end that links to the new platform, which might be Linux running on Itanium. Sitting between this front end and back end is an optimizer layer that translates blocks of instructions in the Irix-MIPS application into an intermediate form, which Transitive calls intermediate representation, or IR. The optimizer, as the name suggests, performs optimizations on these blocks of instructions and stores these routines in the cache of the server, in the case the Linux-Itanium box. The optimizer then encodes the binaries for the new target environment and handles all of the operating system and graphics mapping calls, which allows the application to run. QuickTransit can support any operating system that is Unix-like or Linux-like as a source application platform and move it to any other Unix-like or Linux-like platform; also, the software can move any applications (including the operating systems) that run on IBM mainframes to a Unix or Linux platform. There are four variants of the code. QuickTransit for Itanium supports MIPS, Power/PowerPC, X86, and mainframe binaries; QuickTransit for Opteron supports MIPS, Power/PowerPC, and mainframe binaries; QuickTransit for X86 supports MIPS, Power/PowerPC, and mainframe binaries; and QuickTransit for Power/PowerPC supports MIPS, X86, and mainframe binaries. QuickTransit does not yet support Sparc or PA-RISC applications from the Unix platforms of Sun Microsystems or Hewlett-Packard, but Transitive is pondering the possibilities.

End users cannot buy QuickTransit--at least not yet, anyway. Transitive plans to sell the software to companies that make gaming consoles, various consumer electronics, embedded systems, and desktop, workstation, and server makers who are all facing, in one way or another, a legacy software lock in for operating systems and their applications. Platform partners have to pay $250,000 to test their platforms using QuickTransit, and then they have to pay millions of dollars to license the technology for each source-target platform, plus millions a year in usage and maintenance fees.

Despite those costs, SGI likes QuickTransit for two reasons: one, it gets Irix-MIPS workloads moving off its Origin servers and on to its Altix servers rather than some other box, and it can also pass some of the cost of using QuickTransit on to customers, who are only happy to do so because of the big improvement in price/performance and performance they will see in moving from SGI's Irix platforms to its Altix boxes. Jeff Greenwald, senior director of server marketing at SGI, says that the software is being sold primarily on the Altix 350 servers, which are in the middle of the Altix product line and which offer up to 32 processors in a single system image with shared memory, but QuickTransit is an option on smaller and larger Altix machines. While the use of QuickTransit on the Prism workstations was driven primarily to assist ISVs in moving visualization applications on Irix-MIPS to Linux-Itanium, Greenwald says support for QuickTransit on the Altix boxes is about supporting home-grown code that its Irix customers have created on newer iron.

According to Greenwald, many Origin server customers running Irix workloads are sitting out there with 600 MHz, 700 MHz, or 800 MHz MIPS processors, and the current Altix line uses 1.5 GHz or 1.6 GHz Itanium 2 processors, which can deliver 200 to 400 percent better raw performance, on a CPU-to-CPU basis as measured in teraflops, and depending, of course, on the workload and system configuration. Initial benchmark tests of QuickTransit show that it can deliver anywhere from a 100 to 150 percent performance boost, CPU for CPU, moving an Irix application from an Origin server to an Altix server. And because the Altix machines are a lot less expensive, the price/performance improvement compared with expanding Origin machines can be in the range of 200 to 300 percent. Those are big numbers, and ones that are designed to get the attention of the Origin installed base. (These numbers also seem to imply that overhead for running QuickTransit can range from 25 to 60 percent, depending on the workload, but remember that this is thin data since SGI is just getting started.)

So, how big is the target that SGI is chasing with QuickTransit? Greenwald says SGI has identified about 1,000 Origin sites that have an aggregate installed base of more than 20,000 processors; these machines have a vintage that runs from one to about five to six years. Given that customers upgrade their HPC servers every three years or so, that means that about 400 to 500 of those sites comprising about 10,000 processors are looking to upgrade soon. Some of these sites, for their own reasons, will do a real port of their Irix applications to Linux running on Altix boxes, but others will now have the option of using QuickTransit and immediately move their applications to the new platform. And with SGI only charging $38,000 to license QuickTransit on a 32-processor Altix 350 NUMA cluster, this is not going to be a hard sell--not when a decent HPC programmer costs three times that amount a year and the configured Altix server will cost in excess of $200,000 without storage. When you add in storage, services, those Origin sites that are looking to upgrade represent an opportunity well north of $100 million just for raw hardware, and if customers buy lots of excess capacity, probably several hundred million dollars. QuickTransit support could therefore be a big factor in SGI's sales in the next 12 months.

The issue is what Irix applications can make the jump to Altix boxes running Linux and QuickTransit. Any hard-coded, real-time applications cannot make the jump, says Leslie Tung, product manager for SGI's software products. And any application that is keyed to specific Origin hardware peripherals and its device drivers cannot be used where those devices are not supported on the Altix machines. And of course, any application that takes advantage of specific features of MIPS chips or the Irix operating system that are not supported in the Itanium chips or the Linux operating system won't work, either. Tung says for customers concerned about the performance of QuickTransit on Altix, SGI is guaranteeing that, on a CPU-for-CPU basis, the Altix box will deliver performance at least on par with the Origin systems. SGI is targeting customers in the government, manufacturing, research, and academic sectors with the QuickTransit software.