AMD’s Epyc Milan offers double Intel Xeon’s datacenter performance

Enlarge / Whether or not your main ask is larger efficiency per watt, per bodily rack unit, or per TCO greenback, AMD’s Epyc Milan is an especially sturdy contender.

At the moment, AMD launched Epyc Milan, the server / knowledge heart implementation of its Zen 3 structure. The story for Epyc Milan is essentially the identical advised by Ryzen 5000—a number of cores, excessive boost-clock charges, 19 % gen-on-gen uplift, and an terrible lot of well mannered schadenfreude at rival Intel’s expense.

The comparability between AMD and Intel is much more stark within the server room than it was in shopper PCs and workstations, as a result of there is not any “however single thread” to fall again on right here. Intel clung to a single-threaded efficiency lead over AMD for a while even after AMD started dominating in multithreaded efficiency. Though that lead disappeared in 2020, Intel might no less than nonetheless level to near-equal single-threaded efficiency and pooh-pooh the relevance of the all-threaded efficiency it was getting crushed on.

This is not an excuse you can also make within the knowledge heart—Epyc and Xeon Scalable are each aimed squarely at massively multitenanted, all-threads workloads, and Xeon Scalable simply cannot sustain.

Face to face with Xeon Scalable

We’ll get into a number of the architectural modifications in Epyc Milan later, however they’re most likely not a lot shock to readers who’re actually into CPU structure within the first place—the transition from Rome to Milan is a shift from Zen 2 to Zen 3 structure, not a lot totally different within the rack with Epyc Milan than it was on the desktop with Ryzen 5000.

We desire the easy, boots-on-the-ground perspective right here: these are sooner processors than their Xeon opponents, and you will get extra accomplished with much less bodily area and electrical energy with them. AMD offered a slide with a smoothed progress curve that exhibits Epyc lurching into excessive gear in 2017, bypassing Xeon and persevering with to depart its rival within the mud.

We’re not totally sure we agree with the smoothing—Xeon Scalable and Epyc have been at a lifeless warmth in each 2017 and 2018, then Epyc took a really large leap ahead in 2019 with the primary Zen 2. The smoothed curve appears to be attempting to hammer the purpose house that Epyc continues to enhance at a stable fee fairly than stagnating.

There is not any denying the efficiency delta between Epyc and its closest Xeon opponents—and AMD’s presentation leaves no stone unturned within the quest to show it. AMD’s flagship 64-core Epyc 7763 is proven turning in additional than double the efficiency of a Xeon Gold 6285R in Specrate 2017 integer, Specrate 2017 floating level, and Java Digital Machine benchmarks.

Much more impressively, AMD CEO Lisa Su offered a slide displaying 2.12x as many VDI desktop periods operating on an Epyc 7763 system as on a Xeon Platinum 8280 system. The one remaining query is whether or not these are truthful comparisons to start with—some have been in opposition to Xeon Gold, one in opposition to Xeon Platinum, and none is in opposition to essentially the most present Intel line-up. What provides?

There are successfully no publicly accessible benchmarks out there for newer Xeons just like the 8380HL—and so they aren’t any faster than the Xeon Platinum 8280 anyway, even utilizing Intel’s personal numbers. Utilizing the Xeon Gold 6285R in most comparisons is smart additionally—it gives near-identical performance to the Xeon Platinum 8280,on the similar TDP and considerably decrease price.

In different phrases, these numbers are being offered with none “gotchas” that we might discover—AMD is evaluating its flagships to Intel’s in essentially the most cheap head-to-head comparisons attainable.

Architectural modifications from Rome to Milan

Milan gives 19 % larger IPC (directions per clock cycle) than Rome did, largely as a consequence of Zen 3’s improved department prediction, wider execution pipeline, and elevated load/retailer operations per clock cycle.

Zen 3 additionally gives a extra unified L3 cache design than Zen 2 did. This one takes somewhat explaining—Zen 2 / Rome supplied a 16MiB L3 cache for every four-core group; Zen 3 / Milan as a substitute gives 32MiB for every eight-core group. This nonetheless breaks right down to 4MiB of L3 per core—however for workloads wherein a number of cores share knowledge, Zen 3’s extra unified design can add as much as huge financial savings.

If 3MiB of L3 cache knowledge is similar for eight cores, Rome would have wanted to burn 6MiB on it—an similar copy in every of two four-core groupings. Milan, as a substitute, can save the identical 3MiB in a single cache, serving all eight cores. This additionally means particular person cores can handle extra L3 cache—32MiB for Milan to Rome’s 16MiB. The result’s sooner core and cache communication for giant workloads, with corresponding discount in efficient reminiscence latency.

Safety enhancements

AMD’s Epyc has loved a usually higher safety repute than Intel’s Xeon, and for good cause. The Spectre and Spectre V4 speculative execution assaults have been mitigated in {hardware} in addition to on the OS / Hypervisor ranges since Epyc Rome. Milan provides assist for Safe Nested Paging—providing safety for trusted VMs from untrusted hypervisors—and a brand new function referred to as CET Shadow Stack.

The Shadow Stack function helps shield in opposition to Return Oriented Programming assaults, by mirroring return addresses—this permits the system to detect and mitigate in opposition to an assault which efficiently overflows one stack however doesn’t attain the shadow stack. Use of this function requires software program updates within the working system and/or hypervisor.

Epyc Milan CPU fashions

Epyc Milan launches in 15 flavors, starting from the eight-core 72F3 with increase clock as much as 4.1GHz at a 180W TDP as much as the large 7763, with 64 cores, increase clock as much as 3.5 GHz, and 280W TDP.

All Milan fashions supply SMT (two threads per core), 8 channels of DDR4-3200 RAM per socket, 128 lanes of PCIe4, Safe Reminiscence Encryption (encryption of system RAM in opposition to side-channel assaults), Safe Encrypted Virtualization (encryption of particular person VMs in opposition to side-channel assaults from different VMs or from the host), and extra.

The SKUs are grouped into three classes—the best per-core efficiency comes from SKUs with an “F” within the third digit, starting from eight-core/180W 72F3 to 32-core/280W 75F3. (We suspect that the “F” is for quick.)

The subsequent grouping, optimized for highest core/thread depend per socket, beings with “76” or “77” and ranges from the 48C/225W 7643 to 64C/280W 7763. In case you’re on the lookout for essentially the most firepower per rack unit that yow will discover, these must be the primary fashions in your record.

The rest of Milan’s SKU lineup begins with both 73, 74, or 75 and is geared toward a “balanced” profile, seeking to optimize efficiency and TCO. These vary from the 16C/155W 7343P to the 32C/225W 7543.

Lastly, while you see a “P” in any of those SKUs, it denotes a single-socket mannequin.

Discussing Milan with a number one server OEM

After consuming AMD’s knowledge, we spoke to Supermicro‘s Senior VP of Subject Software Engineering, Vik Malyala. Supermicro has already shipped about 1,000 Milan-powered servers to pick out clients, and Malyala briefly confirmed the broad outlines of AMD’s efficiency knowledge—sure, they’re quick, sure, 19 % gen-on-gen uplift is about proper—earlier than we moved onto the actual elephant within the room: provide.

In keeping with Malyala, AMD has acknowledged that the provision chain would not have quite a lot of wiggle room in it this yr. Supermicro was advised it could must forecast its CPU provide must AMD nicely forward of time with a view to get well timed supply—a scenario Malyala says applies to many upstream distributors, this yr.

Though AMD’s guarantees to Supermicro are lower than concrete—they hope to meet orders with “minimal disruption,” given satisfactory forecasting—Malyala says that AMD has hit its delivery targets to date. Supermicro is extending the identical hand-in-hand to its bigger clients as AMD is to its OEMs, describing a technique of wants forecasting coming in from enterprises and knowledge facilities to the OEMs that permit it, too, to ship in a predictable trend.

This kind of superior forecasting and supply is not actually relevant to small companies which could solely purchase a couple of servers as soon as each three to 10 years, in fact. Malyala says these organizations are a “most likely lower than three-week situation” for small, ad-hoc orders.

After we requested in regards to the stage of curiosity and order quantity Supermicro sees for Epyc versus Xeon servers, Malyala merely replied “buyer curiosity [in Milan] has been extraordinarily sturdy.”

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