Assessing Cavium's ThunderX2: The Arm Server Dream Realized At Last
by Johan De Gelas on May 23, 2018 9:00 AM EST- Posted in
- CPUs
- Arm
- Enterprise
- SoCs
- Enterprise CPUs
- ARMv8
- Cavium
- ThunderX
- ThunderX2
Java Performance
The SPECjbb 2015 benchmark has "a usage model based on a world-wide supermarket company with an IT infrastructure that handles a mix of point-of-sale requests, online purchases, and data-mining operations." It uses the latest Java 7 features and makes use of XML, compressed communication, and messaging with security.
Note that we upgraded from SPECjbb version 1.0 to 1.01.
We tested SPECjbb with four groups of transaction injectors and backends. The reason why we use the "Multi JVM" test is that it is more realistic: multiple VMs on a server is a very common practice, especially on these 100+ threads servers. The Java version was OpenJDK 1.8.0_161.
Each time we publish SPECjbb numbers, several people tell us that our numbers are too low. So we decided to spend a bit more time and attention on the various settings.
However, it is important to understand that the SPECJbb numbers published by the hardware vendors are achieved with the following settings, which are hardly suitable for a production environment:
- Fiddling around with kernel settings like the timings of the task scheduler, page cache flushing
- Disabling energy saving features, manually setting c-state behavior
- Setting the fans at maximum speed, thus wasting a lot of energy for a few extra performance points
- Disabling RAS features (like memory scrub)
- Using a massive amount of Java tuning parameters. That is unrealistic because it means that every time an application is run on a different machine (which happens quite a bit in a cloud environment) expensive professionals have to revise these settings, which may potentially cause the application to halt on a different machine.
- Setting very SKU-specific NUMA settings and CPU bindings. Migrating between 2 different SKUs in the same cluster may cause serious performance problems.
We welcome constructive feedback, but in most production environments tuning should be simple and preferably not too machine-specific. To that end we applied two kinds of tuning. The first one is very basic tuning to measure "out of the box" performance, while aiming to fit everything inside a server with 128 GB of RAM:
For the second tuning, we went searching for the best throughput score, playing around with "-XX:+AlwaysPreTouch", "-XX:-UseBiasedLocking", and "specjbb.forkjoin.workers". "+AlwaysPretouch" zeroes out all of the memory pages before starting up, lowering the performance impact of touching new pages. "-UseBiasedLockin" disables biased locking, which is otherwise enabled by default. Biased locking gives the thread that already has loaded the contended data in the cache priority. The trade-off for using biased locking is some additional bookkeeping within the system, which in turn incurs a small performance hit overall if that strategy was not the right one.
The graph below shows the maximum throughput numbers for our MultiJVM SPECJbb test.
The ThunderX2 achieves 80& to 85% of the performance of the Xeon 8176. That should be high enough to beat the Xeon 6148. Interestingly, the top scores are achieved in different ways between the Intel and Cavium systems. In case of the Dual ThunderX2, we used:
Whereas the Intel system achieved best performance by leaving biased locking on (the default). We noticed that the Intel system – probably due to the relatively "odd" thread count – has a slightly lower average CPU load (a few percent) and a larger L3-cache, making biased locking a good strategy for the that architecture.
Finally, we have Critical-jOPS, which measures throughput under response time constraints.
With this many threads active, you can get much higher Critical-jOPS by significantly increasing the RAM allocation per JVM. However, it really surprising to see that the Dual ThunderX2 system – with its higher thread count and lower clockspeed – has a much easier time delivering high throughputs while still keeping the 99th percentile response time under a certain limit.
Increasing the heap size helps Intel to close the gap somewhat (up to x2), but at the expense of the throughput numbers (-20% to -25%). So it seems that the Intel chip needs more tuning than the ARM one. To investigate this further, we turned to "Transparant Huge Pages" (THP).
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imaheadcase - Wednesday, May 23, 2018 - link
I really think Anandtech needs to branch into different websites. Its very strange and unappealing to certain users to have business/consumer/random reviews/phone info all bunched together.Ever since anand actually left it really did venture into more a business/insider based website with random stuff thrown in. It is in no way a bad thing, its just like this review for instance would not appeal to %95 of readers normally. Everyone likes technology naturally that comes to this website, but its a fine line between talking about high end server components that are out of reach to people who just read the article on the mini-itx gaming motherboard. lol
Andrei Frumusanu - Wednesday, May 23, 2018 - link
You're always free to skip articles, nobody's forcing you to read it.boeush - Wednesday, May 23, 2018 - link
I guess he'd prefer the site content to be grouped in some manner roughly mirroring market segmentation. For instance: consumer, professional, enterprise, exotic/HPC. As opposed to jumbling everything together. Personally, I don't mind - but then, I'm not known for obsessive-compulsive organizing, either :)BurntMyBacon - Thursday, May 24, 2018 - link
Given the large differences in tech, focus, needs, and trends, I wouldn't mind breaking out Phones and perhaps servers into their own sections. I think there is more than enough overlap to keep consumer and professional desktop/laptop/workstation together, but that is entirely up to how deeply you want to divide things up. On the other hand, you'll want all of it to show up on the front page in some form, or it'll look like the site doesn't have much activity. Perhaps separate pipelines for each category could work. That all said, I don't really mind just skipping over articles that don't interest me. :)imaheadcase - Thursday, May 24, 2018 - link
Please, that is just lazy excuse. Even news websites have catagory based on the news you interested in. Anandtech literally had a review of a gaming motherboard then a high end server thing, and newz feed gets filled with phone and other news.name99 - Thursday, May 24, 2018 - link
God, you must REALLY hate Twitter then...I argue with Andrei a lot, but every so often he writes a sentence like "You're always free to skip articles, nobody's forcing you to read it" that makes me want to clap him on the back and say "yes, YOU get it" :-)
Threska - Sunday, May 27, 2018 - link
Taken to it's logical extreme the front page could be a dumping ground cesspool and the retort would be "you don't have to wade through any of it" which sounds witty but doesn't solve anything, but over time would lead to the predictable outcome of people leaving.imaheadcase - Sunday, May 27, 2018 - link
I do hate twitter, but because it has no valid purpose other than to get customer service done faster with companies because it reflects more on them because public venue. Its mostly just a rant inducing place, or a place that is basically just texting anyways since everyone just wants you to send a DM.The whole idea of saying "you are free to skip it" is kinda silly thing to say on the internet now. Especially since more and more you can filter things according to what you want. Not only that, but with the tight competition with views from tech websites its in best interest to have more options.
Even the layout of website never changed. I mean have you ever been to website without a adblocker on? They don't even advertise tech related stuff on it. Its just stupid clickbait stuff.
Keep in mind, this is not a complaint about articles itself, its just how they are posted. I love this site, been coming to it ever since i built first pc when i was a kid. But its focus is all over the place now vs years ago out what its posting. I'm half thinking one day i will see a review of electronic toothbrush then next day new CPU.
GreenReaper - Monday, June 4, 2018 - link
I'd be fine with that, as long as it was the best darn toothbrush in town!Threska - Sunday, May 27, 2018 - link
Accessing through RSS might be a better solution especially with a good reader. Just needs accurate tags to match.