Messages in this thread | | | Date | Wed, 17 Jun 2015 21:06:17 +0800 | From | Boqun Feng <> | Subject | Re: [Resend PATCH v8 0/4] sched: Rewrite runnable load and utilization average tracking |
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Hi Yuyang,
On Wed, Jun 17, 2015 at 11:11:01AM +0800, Yuyang Du wrote: > Hi, > > The sched_debug is informative, lets first give it some analysis. > > The workload is 12 CPU hogging tasks (always runnable) and 1 dbench > task doing fs ops (70% runnable) running at the same time. > > Actually, these 13 tasks are in a task group /autogroup-9617, which > has weight 1024. > > So the 13 tasks at most can contribute to an average of 79 (=1024/13) >
[snip]
> So the problem is: > > 1) The tasks in the workload have too small weight (only 79), because > they share a task group. > > 2) Probably some "high" weight task even runnable a small time > contribute "big" to cfs_rq's load_avg.
Thank you for your analysis.
Some updates:
I created a task group /g and set /g/cpu.shares to 13312 (1024 * 13), and then ran `stress --cpu 12` and `dbench 1` simultaneously in that group. The situation is much better, only one CPU is not fully loaded, and its utilization rate stays around 85%.
Regards, Boqun [unhandled content-type:application/pgp-signature] | |