Re: Potential scheduler regression

From: Ben Guthro
Date: Fri Jul 07 2017 - 16:55:40 EST

On Wed, Jul 5, 2017 at 12:48 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Wed, Jul 05, 2017 at 11:42:46AM -0400, Ben Guthro wrote:
>> Hello,
>> I've been in the process of updating our kernel in our appliance VM
>> from an old LTS kernel (4.1.y) to something a bit more modern (4.9.y)
>> - and ran into a performance regression, when our QA team was running
>> some regression suites.
>> I bisect this behavior to the following commit, introduced in the 4.9
>> merge window:
> Could you test a later kernel that includes commit:
> 1ad3aaf3fcd2 ("sched/core: Implement new approach to scale select_idle_cpu()")

(resend without html)

Apologies on the delay - it took a bit to get the machines, to run the test.

I am happy to report that the kernel at 1ad3aaf3fcd2, seems to regain
performance loss from 1b568f0aab, in our test environment.

Since 4.9 is an LTS kernel - is this appropriate to suggest to be
included in the linux-stable list?