erichileman

I've been load testing z1d last couple days and cpu's are always set at the base 3.4GHz. Turbostat doesn't run (likely due to kvm hybrid on nitro). Tried changing the cstate to 1 but always showing 9. I can only see 1 core go up to ~4GHz and only for a fraction of a second and only a handful of times. All other times they stay at 3400GHz. I opened a case with aws ec2 support team who doesn't know what's going on. They said they are escalating to the development and hypervisor teams.

Has anyone else tested the z1d and been able to get "sustained all core turbo" of up to 4GHz?

sauces:

https://aws.amazon.com/about-aws/whats-new/2018/07/introducing-amazon-ec2-z1d-instances/

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/processor_state_control.html

E3-1240 v5 @ 3.50GHz performance is worse than E5-2650 v2 @ 2.60GHz for PHP 5.X. For PHP 7 (and everything else) the E3 is better.

The test setup is Xenserver 6.5 w/Centos 6.8 kernel 2.6.32-642.6.2.el6.x86_64 HVM guests. Each VM has 2 cores assigned. The test is using siege. PHP 5.4, 5.5, 5.6; are all nearly 50% slower for E3. PHP 7 is 200% faster for E3. Varnish is nearly 300% faster for E3. Sysbench tests are 150% - 300% faster for E3. Only PHP 5.X is faster for E5.

I've torn down and rebuilt the VM's several times and confirmed they are the same. I've even live migrated them across to the other host/proc and confirmed the same results.

I've tried strace, but it isn't going to work because it adds overhead to every call and the E3 executes that overhead faster. In a browser the E5 TTFB is 167ms; the E3 is 318ms. Stracing the call on the E5 is 548ms; E3 557ms. The E3 executes the overhead of strace faster and the execution times equalize.

What is different about PHP 5.X that it would run so much better on the older generation, slower clocked, E5? Is it the larger l1/l2 cache making the difference? Or something else, instruction set related maybe? What another tool could I use, that adds a little overhead, to see the php execution performance?