linux-kernel - Re: [PATCH] sched/tracing: correct the task blocking state

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Message-ID: <xhsmhbka2jzaj.mognet@vschneid-thinkpadt14sgen2i.remote.csb>
Date: Wed, 03 Jan 2024 14:56:36 +0100
From: Valentin Schneider <vschneid@...hat.com>
To: Alex Shi <seakeel@...il.com>
Cc: alexs@...nel.org, Ingo Molnar <mingo@...hat.com>, Peter Zijlstra
 <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, Vincent
 Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann
 <dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, Ben
 Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, Daniel Bristot
 de Oliveira <bristot@...hat.com>, linux-kernel@...r.kernel.org,
 curuwang@...cent.com
Subject: Re: [PATCH] sched/tracing: correct the task blocking state

On 03/01/24 11:14, Alex Shi wrote:
> On Wed, Jan 3, 2024 at 12:16 AM Valentin Schneider <vschneid@...hat.com> wrote:
>>
>> Why is that an issue? If those tasks didn't have to be
>> TASK_UNINTERRUPTIBLE (via TASK_IDLE), we'd make them TASK_INTERRUPTIBLE and
>> they'd also inflate the 'sleeping' schedstat (rather than the 'blocked').
>>
>> What problem are you facing with those tasks being flagged as blocked during
>> their wait?
>>
>
> Uh, Tencent cloud has some latency sensitive services, a blocked state
> means the service has
>  some trouble, but with IDLE state involved, it's failed on this judgement.
> and 2nd, if a service has abnormal, we want to check if it's hanging
> on io or sth else, but the top
> 3 D tasks are often queuework in our system, and even a task in
> blocked state we have no
> quick way to figure out if it's IDLE or BLOCKED.  2 different states
> will help us a lot.
>

That's useful information - generally it's good to add the motivation for a
patch in the changelog.

> Thanks!