On 16.05.2016 14:18, Peter Zijlstra wrote:
On Mon, May 16, 2016 at 12:36:19PM +0300, Konstantin Khlebnikov wrote:
This feature allows to change cpu cgroup weight for a limited time.
Cgroup interface:
cpu.cfs_reserve_us - reserved time for each cpu.cfs_period_us
cpu.cfs_reserve_shares - group weight during reserved time
While cfs group consumes reserved cpu time it has different weight,
thus it gets different vruntime penalty for that execution.
^ weight
|
|
reserve |
shares -------*
| |
| |
| |
shares - *-----------------*
| |
| |
0------|-----------------|-----------> time
reserve quota
Reserve can work as a "low limit": boost weight for "guaranteed" time,
and as a "high limit": give normal weight for a limited time and allow
utilize cpu when nobody else needs it.
You forgot to explain why I should care about this.
As I told this works as low-limit or high-limit which allow to
control cpu time distribution without hard limits and throttling.
Present quota/hard limit has well known problems when it throttle task
inside kernel where it holds mutexes. Also it's too strict and doesn't
allow utilization of unused cpu time.
--
Konstantin
