Re: [PATCH] sched/deadline: Fix BUG_ON condition for deboosted tasks

Ankit Jain
2022-07-19T05:30:29Z

> On 18-Jul-2022, at 6:31 PM, Juri Lelli <juri.lelli@redhat.com> wrote:
>
> ⚠ External Email
>
> On 18/07/22 07:46, Ankit Jain wrote:
>
> ...
>
>> Hi Juri,
>>
>> Actually, while testing I already included below commits in 4.19-rt :
>>
>> feff2e65efd8d84cf831668e182b2ce73c604bbb (sched/deadline: Unthrottle PI boosted threads while
>> enqueuing)
>> 46fcc4b00c3cca8adb9b7c9afdd499f64e427135 (sched/deadline: Fix stale throttling on de-/boosted tasks)
>> 2279f540ea7d05f22d2f0c4224319330228586bc (sched/deadline: Fix priority inheritance with multiple)
>> 0e3872499de1a1230cef5221607d71aa09264bd5 (kernel/sched: Remove dl_boosted flag comment)
>
> Interesting.
>
> Is the workload you are using to test this easily reproducible? I'd like
> to try that out on my end to check if I see the same (of course the
> issue I was working on goes away with my fix :).
>
> Best,
> Juri
>

Hi Juri,

The test with which i am able to hit the issue is as follows:
• Schedule SCHED_FIFO/55 (sched_priority = 55) tasks running infinite loop on all isolated cores.
• spwan 30-40 docker containers in loop (docker load , docker run)
• Immediately after that schedule SCHED_FIFO/55 (sched_priority = 55) tasks running infinite loop on all isolated cores again.
• BUG_ON gets hit almost every time.
System config as follows:
• 4.19-rt kernel
• 40 cpu (0-1 housekeeping, 2-39 isol cpus)
• stalld-1.3.0 with the fixes from latest version (for task starvation avoidance), "tuned" with real-time profile

Thanks.