ARM processors have been trying to make a place for themselves in the server world for several years, with very limited success so far. Amazon, the number one in the segment, offers them in AWS’ huge EC2 range, but this is almost the only recent example still on the market. In France, Scaleway had tried this bet a few years ago, but Iliad’s subsidiary now relies mainly on x86 servers.
However, Ampere Computing, a Californian start-up founded by Renée James who spent much of her career at Intel, hopes to reverse the trend with the Altra, an ARM processor based on the N1 architecture. With 80 cores clocked at 3GHz and a 210-watt TDP, it’s supposed to outperform Intel-designed Xeon for servers. Its designers have put forward a very impressive figure, with performance more than twice as high as an Intel Xeon Platinum 8280, a 28-core processor with 2.7 GHz.
Faced with this figure, how can we not marvel at the advances of ARM processors? To the point of suggesting, as Jean-Louis Gassée did in his weekly column, that Apple could easily switch the Mac Pro to an ARM processor. The workstation based on Xeon processors, the conclusion may seem logical, except that it does not last long. And for good reason, the performance tests presented by Ampere at the same time as its Altra are borderline false advertising.
The official communication highlights performance similar to an AMD processor and twice as much as an Intel processor. But the main thing on this slide provided by Ampera is the words “Refer to end notes for details.”
These performance measures provided by the designer of Altra pose several problems. To begin with, the manufacturer has conducted only part of the benchmark in the industry, forgetting the tests that would put its processor in trouble on the pretext that they do not make sense in the world of servers. This can still be justified, but the manufacturer has also lowered the results of x86 processors from 16 (AMD) to 24% (Intel). This choice is explained by differences in compilers that end up in real use, but a bench is precisely supposed to measure actual performance.
To make matters worse, all the communication clearly suggests that the comparison is made between an Intel processor, an AMD processor and an ARM processor. But Ampere provided “final notes” associated with benchmarks and they reveal that the comparison was made with a duo of Altra, this new processor can work in pairs. It is common in the industry and it is a positive that this newcomer can work that way, but it totally distorts the comparison.
This newcomer does twice as much as the Xeon by mobilizing no less than 180 hearts and with a 360W TDP! With a single ARM processor, we would logically have performance similar to that of Intel and lower than the AMD model. And the list is not even finished: we also learn in these notes that the tests were carried out with prototypes of Altra that are timed at a speed higher than the processor actually marketed. The cores were running at 3.3 GHz, while Ampere sells a blocked processor at a maximum of 3GHz.
The Altra cannot exceed 3 GHz in theory, but the tests were conducted with a prototype at 3.3 GHZ.
This is enough to present more favorable benches for the press, but we should probably not expect to have real performance twice as high as with a server built around a Xeon. Interestingly, however, the speed of 3 GHz can be maintained permanently on high-end configurations. This is not a temporary maximum value as proposed by Intel’s Turbo Boost mode, the Altra should be able to run continuously at this level.
Nevertheless, this new processor is interesting in the world of servers thanks to its specialization on virtualization. VPS-type virtual instances have become widespread, as have Docker and Kubernetes-based solutions with the same idea of sharing server resources1 each time. The Altra was designed with this use in mind and especially with the idea of better securing each virtual machine installed on the server.
Ampere has chosen to multiply hearts rather than threads: there are 80 hearts and 80 threads, which means that there is no multi-threading. Several flaws in Intel processors are linked to this technology that allows for more threads, and these vulnerabilities are particularly annoying in a server context, where multiple virtual instances share the same processor2. The Altra isolates each heart to the maximum, offering them L1 (64KB per heart) and L2 (1 MB per heart) dedicated caches.
The two reference servers designed by Ampere to accompany the marketing of the Altra.
Even if the performance will not be as good as its designers would like to say, the Altra should be a server processor as complete as its competitors on other points. It will be able to handle up to 4TB of DDR4-3200 RAM per processor, with support for ECC protection that is often essential in a server. Ampere has also integrated 128 PCIe 4.0 lanes, 32 of which will be used to connect two chips in bi-proc configurations. In total, a server will have 192 PCIe 4.0 lanes and 8TB of RAM.
Ampere also introduced two reference configurations for 1U and 2U servers, with one or two processors. The Altra will start to be marketed from now on, knowing that the company has partnered with TSMC for production in 7 nm. Public prices are not known, nor is actual availability at hosts.
One thing is certain anyway: this processor would be a very bad candidate for the Mac Pro. This is not to say that Apple will never be able to abandon Intel or even the x86 architecture on this machine. But if the tower went to ARM, it would probably be with a processor built from very different choices. And it probably wouldn’t be for now, we expect MAC portable ARM at first.
The traditional model of hosting was to rent a full server, which you were the only one who could use. Now, the most common model is virtualization, where you “rent” a virtual server that runs on a large dedicated server shared between tens or hundreds of virtual servers. This model has significantly reduced hosting costs.
In the virtual server model, each instance is theoretically perfectly isolated from the others. This is an important prerequisite, otherwise data from all virtual servers that operate on the same dedicated server would be freely accessible. Processor security vulnerabilities, particularly related to Intel, can challenge this insulation, even if the biggest flaws have been fixed quickly.