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

[Peter Zijlstra]

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... ?