linux-kernel - Re: [PATCH v6 0/2] sched/deadline: Fix and optimize sched_dl_global

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Date:   Sun, 18 Oct 2020 10:27:18 +0200
From:   Daniel Bristot de Oliveira <bristot@...hat.com>
To:     Juri Lelli <juri.lelli@...hat.com>, Peng Liu <iwtbavbm@...il.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, valentin.schneider@....com, raistlin@...ux.it
Subject: Re: [PATCH v6 0/2] sched/deadline: Fix and optimize
 sched_dl_global_validate()

Hi,

On 10/14/20 3:32 PM, Juri Lelli wrote:
> Hi,
> 
> On 08/10/20 23:47, Peng Liu wrote:
>> When change global rt bandwidth, we check to make sure that new
>> settings could accommodate the allocated dl bandwidth.
>>
>> Under SMP, the dl_bw is on a per root domain basis, currently we check
>> and update the new settings one cpu by one cpu, but not in the unit of
>> root domain, which is either overdoing or error.
>>
>> patch 1 removed the superfluous checking and updating
>> patch 2 fixed the error validation
>>
>> For details, please see the corresponding patch.
>>
>> ----------------
>> v6 <-- v5:
>>  - no functional changes, just revert visit_gen back to u64;
>>
>> v5 <-- v4:
>>  - no functional changes, just split the v4 single patch to two to
>>    obey the "one patch do only one thing" rule;
>>  - turn root_domain::visit_gen from u64 to u32;
>>    both suggested by Juri.
>>  - refine changelog;
>>
>> v4 <-- v3:
>>  - refine changelog;
>>  - eliminate the ugly #ifdef guys with Peter's method;
>>
>> v3 <-- v2:
>>  - fix build error for !CONFIG_SMP, reported by kernel test robot;
>>
>> v2 <-- v1:
>>  - replace cpumask_weight(cpu_rq(cpu)->rd->span) with dl_bw_cpus(cpu),
>>    suggested by Juri;
>>
>> Peng Liu (2):
>>   sched/deadline: Optimize sched_dl_global_validate()
>>   sched/deadline: Fix sched_dl_global_validate()
>>
>>  kernel/sched/deadline.c | 44 +++++++++++++++++++++++++++--------
>>  kernel/sched/sched.h    | 51 ++++++++++++++++++++++-------------------
>>  kernel/sched/topology.c |  1 +
>>  3 files changed, 63 insertions(+), 33 deletions(-)
> 
> These look now good to me. Thanks a lot!
> 
> Acked-by: Juri Lelli <juri.lelli@...hat.com>


I just found a minor thing in a comment:

"It's *monotonously* increasing."

I tried to find the usage of "monotonously increasing" for monotonic functions,
and I did not find it. The (as least most used) term is "monotonically," so the
sentence would be like "It is a monotonically increasing value." But it is just
a minor thing. Anyways:

Reviewed-by: Daniel Bristot de Oliveira <bristot@...hat.com>

Thanks!
-- Daniel