linux-kernel - Re: [PATCH 2/3] delayacct: convert task->delays to a object

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Message-ID: <a93f13de-a018-2ee4-c7a0-855c3bd04444@gmail.com>
Date:   Mon, 9 Oct 2023 18:29:15 +0800
From:   brookxu <brookxu.cn@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     bsingharora@...il.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] delayacct: convert task->delays to a object


在 2023/10/9 16:43, Peter Zijlstra 写道:
> On Sun, Oct 08, 2023 at 07:10:01PM +0800, brookxu wrote:
>
>>>> @@ -1331,7 +1332,7 @@ struct task_struct {
>>>>    	struct page_frag		task_frag;
>>>>    #ifdef CONFIG_TASK_DELAY_ACCT
>>>> -	struct task_delay_info		*delays;
>>>> +	struct task_delay_info		delays;
>>>>    #endif
>>> Yeah, no.
>> Yes, this way will increase about 80 bytes for task_struct, about 0.85% of
>> size of task_struct, I think this just like sched_statistics, so that can
>> better support dynamically enable through sysctl.
> But it's 80 bytes 'nobody' will use. And arguably we should do the same
> with schedstats, that's default disabled and again, that's per-task
> storage nobody ever uses.
>
> Per this argument we can grow task_struct indefinitely until it
> collapses in on itself by the sheer weight of it's information density.
> Every additional field will be a smaller fraction of the total.
>
> Yes, it makes it all a little more cumbersome, but we should really not
> burden everybody with the load of some.
>
> Surely there is another solution... ?
Thanks, agree with you, I try do it in other ways :)