Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-12 Thread Peter Zijlstra
On Thu, Feb 08, 2018 at 02:19:55PM -0800, Rohit Jain wrote: > This patch introduces the sysctl for sched_domain based migration costs. > These in turn can be used for performance tuning of workloads. Smells like a bad attempt to (again) revive commit: 0437e109e184 ("sched: zap the migration

Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-09 Thread Mike Galbraith
On Fri, 2018-02-09 at 12:33 -0500, Steven Sistare wrote: > On 2/9/2018 12:08 PM, Mike Galbraith wrote: > > > Shrug. It's bogus no mater what we do. Once Upon A Time, a cost > > number was generated via measurement, but the end result was just as > > bogus as a number pulled out of the ether.  

Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-09 Thread Steven Sistare
On 2/9/2018 12:08 PM, Mike Galbraith wrote: > On Fri, 2018-02-09 at 11:10 -0500, Steven Sistare wrote: >> On 2/8/2018 10:54 PM, Mike Galbraith wrote: >>> On Thu, 2018-02-08 at 14:19 -0800, Rohit Jain wrote: This patch introduces the sysctl for sched_domain based migration costs. These in

Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-09 Thread Mike Galbraith
On Fri, 2018-02-09 at 11:10 -0500, Steven Sistare wrote: > On 2/8/2018 10:54 PM, Mike Galbraith wrote: > > On Thu, 2018-02-08 at 14:19 -0800, Rohit Jain wrote: > >> This patch introduces the sysctl for sched_domain based migration costs. > >> These in turn can be used for performance tuning of

Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-09 Thread Steven Sistare
On 2/8/2018 10:54 PM, Mike Galbraith wrote: > On Thu, 2018-02-08 at 14:19 -0800, Rohit Jain wrote: >> This patch introduces the sysctl for sched_domain based migration costs. >> These in turn can be used for performance tuning of workloads. > > With this patch, we trade 1 completely bogus

Re: [RFC 2/2] Introduce sysctl(s) for the migration costs

2018-02-08 Thread Mike Galbraith
On Thu, 2018-02-08 at 14:19 -0800, Rohit Jain wrote: > This patch introduces the sysctl for sched_domain based migration costs. > These in turn can be used for performance tuning of workloads. With this patch, we trade 1 completely bogus constant (cost is really highly variable) for 3, twiddling