The Intel Xeon E5 v4 Review: Testing Broadwell-EP With Demanding Server Workloads
by Johan De Gelas on March 31, 2016 12:30 PM EST- Posted in
- CPUs
- Intel
- Xeon
- Enterprise
- Enterprise CPUs
- Broadwell
A Modest Tick
As Broadwell is a tick - a die shrink of an existing architecture, rather than a new architecture - so you should expect modest IPC improvements. Most Xeon E5 v4 SKUs have slightly lower clockspeeds compared to their Haswell v3 brethren, so overall the single threaded performance has hardly improved. Clock for clock, Intel tells us that their simulation tools show that Broadwell delivers about 5% better performance per clock in non-AVX2 traces.
First Y-axis + bars: simulated single threaded performance improvement. Blue line + second Y-axis is the cumulative improvement.
In that sense, Broadwell is basically a Haswell made on Intel's 14nm second generation tri-gate transistor process. Intel did make a few subtle improvements to the micro-architecture:
- Faster divider: lower latency & higher throughput
- AVX multiply latency has decreased from 5 to 3
- Bigger TLB (1.5k vs 1k entries)
- Slightly improved branch prediction (as always)
- Larger scheduler (64 vs 60)
None of these improvements will yield large performance improvements. The larger improvements must come from other features.
New Features
Compared to Haswell-EP, Broadwell-EP also includes some new features. The first one is the improved power control unit.
On Haswell, one AVX instruction on one core forced all cores on the same socket to slow down their clockspeed by around 2 to 4 speed bins (-200,-400 MHz) for at least 1 ms, as AVX has a higher power requirement that reduces how much a CPU can turbo. On Broadwell, only the cores that run AVX code will be reducing their clockspeed, allowing the other cores to run at higher speeds.
The other performance feature is the vastly improved PCLMULQDQ (carry-less multiplication) instruction: throughput has been doubled, and latency reduced from 7 cycles to 5.
This increases AES (symmetric) encryption performance by 20-25%, and CRCs (Cyclic Redundancy check) are up to 90% faster. Broadwell also has some new ADCX/ADOX instructions to speed up asymmetric encryption algorithms such as the popular RSA. These improvements are implemented in OpenSSL 1.0.2-beta3. But don't expect too much from it.. The compute intensive asymetric encryption is mostly used to initiate a secure connection. Most modern web applications keep their sessions "alive", and as a result, events that require asymmetric encryption happen a lot less frequentely . Symmetric encryption (like AES) which is used to send encrypted data is a lot lighter, so even on a fully encrypted website with long encrypted data streams, encryption is only a small percentage (<5%) of the total computing load.
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xrror - Tuesday, April 5, 2016 - link
Even at 3.3Ghz though, they shouldn't be that slow. I'm taking a guess - if this was a student lab, and they bothered to specifically order xeon (or opteron back in the day) workstations - I'm guessing this was a CAD/CAM lab or something running a boatload of expensive licenced software (like, autodesk, solidworks, etc) and some of that stuff is horrible at thrashing on the hard drive, constantly.And I doubt your school could spring the cash for SSD drives in them (because Workstation SKU == you pay dearly OEM workstation 'certified' drive cost).
This is all guesses though. And not trying to defend - it does suck when you have what should be a sweet machine choking for whatever reason, and you're there trying to get your assignments done and you just want to smash the screen cause it just chhhuuuuuuggggsss... ;p
SkipPerk - Friday, April 8, 2016 - link
I have seen this many times, even in the for-profit sector. I once saw a compute cluster that was choking on server with slow storage. They had a 10 gb network and fast Xeon machines running on flash, but the primary storage was too slow. When they get a proper SAN it was an order of magnitude improvement.Back in the day storage was often the bottleneck, but it still comes up today.
someonesomewherelse - Thursday, September 1, 2016 - link
We ran everything in virtual machines with the actual disk images not stored locally.... and the lans in the classrooms were 100mbit, idk about the connection from the classroom to the server with the image. How's that for slow?I would have loved it if our stuff was as 'slow' as yours. The wifi in the classrooms was very fast too..... especially since I doubt anyone bothered with turning of their torrents (well I mean it's completely understandable, you are going to watch the new episode of your favorite show once you are back home and not everyone had (well has, but most people can get it now) fth with at least 100Mbit line (ideally symmetrical, but some isps are too gready with ul speeds so 300/50 is cheaper than 100/100...... and good luck getting 1000/1000 on a residential package (the hw isn't the problem since you can get 1000/1000 with a commercial (aka over priced) package..... using the same hw... basically I would just need to sign a new contract, send it back, and enjoy the faster line in 1 business day or less)...well at least there are no bw caps (if I didn't read foreign boards bw caps on non mobile connections would be something I'd think no isp could do and not lose all customers) and there's we have no dmca (or something similar) and afaik no plans for one either (if they tried to pass such a law I can imagine that you'd have enough support for a referendum which you would win with a huge mayority), even better, the methods used to catch people downloading torrents are illegal anyway so any evidence obtained with them or derived from them is inadmissible anyway and just by presenting it you have admitted to several crimes which the police and prosecution are obliged to investigate/prosecute.... copyright infringment however is a civil matter).
donwilde1 - Tuesday, April 5, 2016 - link
One of the more interesting Intel features, in my opinion, is that Broadwell carries an on-board encryption engine with its own interpreter similar to a small-memory, embedded JVM. This enables full Trusted Boot capability, which I view as a necessity in today's hackable world. Would you consider a follow-on article on this? The project was a clean-room development called BeiHai, done in China.JamesAnthony - Wednesday, April 6, 2016 - link
From what I can tell in looking over the benchmarks, there is not much of an increase in performance at all in core vs core performance speeds going from the V1 CPUs to the V4 CPUsAs if you look at the benchmarks, and calculate that you are comparing 16 cores to 44 cores, the 44 core setup is not 2.75x faster.
So while your overall speed goes up, your work accomplished per core is not increasing at the same rate.
Why does this matter? Well thanks to software licensing costs, as you add cores it gets very expensive quickly. So if your software costs (which can easily exceed the hardware costs very quickly) go up with each core you add, but the work done does not, you quickly wind up in a negative cost / performance ratio.
For quite a few people the E5-2667 v2 CPU with 8 cores at 3.5 GHz (Turbo 4) comes out around the best value for the software licensing cost.
So while Intel puts out processors that overall can do more work than the previous ones, the move to per core software licensing is making it a negative value proposition. This is why people keep wanting higher clock speed lower core count processors, but we seem stuck around 3.5 GHz for many years.
SkipPerk - Friday, April 8, 2016 - link
Although you are right for workstations, so much demand is for generic virtualized machines. Many buyers are fine with 2 ghz with as many cores as they can get. They load as little RAM as the spec requires and throw out the cheapest single core, dual thread 2 GB RAM VM they can. This is how call centers work, not to mention many low-level office jobs. They do not care about performance because this is more than enough.I have had specialty applications where prosumer 6-core or 8-core CPUs were the better deal (usually liquid cooled and overclocked), but not many buyers are licensing insanely expensive analytical software by the core.
SeanJ76 - Sunday, April 10, 2016 - link
@Xeon chips!! TOTAL GARBAGE!legolasyiu - Wednesday, April 20, 2016 - link
The ASUS Workstation/Server board with V4 boards are very stable and they have 10% OC. I am very interested how the processor with those boards.Bulat Ziganshin - Saturday, May 7, 2016 - link
>This increases AES (symmetric) encryption performance by 20-25%PCLMULQDQ implements part of Galois Field multiplication and bdw actually improved only GCM part of AES-GCM algo. neither AES nor other popular symmetric encryption algos became faster
oceanwave1000 - Monday, May 9, 2016 - link
This article mentioned that the Broadwell EP e5-v4 family has 3 die configurations. I got the 306mm2 and 454mm2. Did anyone catch the third one?Thanks.