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
Application Development: Linux Kernel Compile
A more real world benchmark to test the integer processing power of our Xeon servers is a Linux kernel compile. Although few people compile their own kernel, compiling other software on servers is a common task and this will give us a good idea of how the CPUs handle a complex build.
To do this we have downloaded the 3.11 kernel from kernel.org. We then compiled the kernel with the "time make -jx" command, where x is the maximum number of threads that the platform is capable of using. To make the graph more readable, the number of seconds in wall time was converted into the number of builds per hour.
A kernel compile does not scale perfectly with more cores, but the Xeon E5-2699 v4 offers up to 2.7 times better performance than the Xeon it is supposed to replace. This kind of workload really seems to favor the new Broadwell core: even at slightly lower clockspeeds, the 18 core Xeon E5-2695 v4 beats the v3 version with the same number of cores by 9%.
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SkipPerk - Friday, April 8, 2016 - link
"Anyone putting Microsoft on bare hardware these days is nuts"This brother is speakin the truth!
warreo - Thursday, March 31, 2016 - link
Can someone clarify this line for me?"The average performance increase versus the Xeon E5-2690 is 3%, and the Broadwell cores get a boost of no less than 19%."
Does that mean IPC increase is 19% for Broadwell, offset by ~16% decline in clockspeed to get to 3% average performance increase? But that doesn't make sense to me as a 3.8ghz (E5-2690) to 3.6ghz (E5-2699 v4) is only 5% decline in max clockspeed?
ShieTar - Thursday, March 31, 2016 - link
I understood it as "the -Ofast setting boosts Broadwell by 19%", so with the -O2 setting it was actually 16% slower than the 2690.And I think the AT-Theory based on the original measurements is that the 3.6GHz boost are not even held for a significant amount of time, so that Broadwell in reality comes with an even worse decline in clock speed.
warreo - Thursday, March 31, 2016 - link
Your interpretation makes much more sense than mine, but still doesn't quite add up. The improvement from using -Ofast vs. -O2 is 13% on average, and the lowest improvement is 4% on the xalancbmk, well below the "no less than 19%" quoted by Johan.Perhaps the rest of the disparity is normalizing for sustained clock speeds as you suspect? Johan is that correct?
Ryan Smith - Thursday, March 31, 2016 - link
I've reworded that passage to make it clearer. But ShieTar's interpretation was basically correct."Switching from -O2 to -Ofast improves Broadwell-EP's absolute performance by over 19%. Meanwhile the relative performance advantage versus the Xeon E5-2690 averages 3%. "
JohanAnandtech - Thursday, March 31, 2016 - link
That means that the -ofast has much more effect on the Broadwell. I mean by that that -ofast is 19% faster than -o2 on Broadwell, while it is 3% faster on Sandy Bridge. I assume that the older the architecture, the better the compiler is able to optimize it without special tricks.warreo - Friday, April 1, 2016 - link
Thanks for the clarification. Loved the review, great work Johan!Pinn - Thursday, March 31, 2016 - link
I'm still happy I went with the 6 core x99 over the 8 core. Massive core count is nice to see available, but I don't see the true value. Looks like you have to do the same rough math to see if the clock speed reduction is worth the core count.Oxford Guy - Tuesday, April 5, 2016 - link
Why would there be "true value" for six and not for eight?Pinn - Wednesday, April 6, 2016 - link
Single threaded workloads.