[PATCH][SRU Vivid] High CPU usage of kworker/ksoftirqd

[Tim Gardner]

On 08/17/2015 02:34 AM, AceLan Kao wrote:
> [Impact] 
> 
>  * Many new platforms have this kind of issue that CPU loading is always
> above 1. We see kworker/ksoftirqd becomes CPU hogger that not only affects
> system performance, but also power consumption.
> 
>   PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
>    23 root 20 0 0 0 0 R 71.6 0.0 17:30.13 kworker/2:0
>    22 root 20 0 0 0 0 S 28.6 0.0 7:00.61 ksoftirqd/2
> 
>  * From upstream we found this commit fix the issue.
> 9250ae mmc: core: Enable runtime PM management of host devices
> 
> [Test Case]
> 
>  * This issue could be found on new skylake machines, just boot up by latest
> Ubuntu kernel 3.19.0-26 and run top to monitor the CPU usage. It should be
> always shows above 1.
> 
>  * With the patch, the CPU loading is around 0.3 after idle for 10 mins.
> 
> Ulf Hansson (1):
>   mmc: core: Enable runtime PM management of host devices
> 
>  drivers/mmc/core/core.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 

Acelan - these patches look fine, but need a bug link. I'd also like to
see some regression test results for non-Skylake platforms in the bug
report.

rtg
-- 
Tim Gardner tim.gardner at canonical.com