Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

Tejun Heo
2020-06-19T22:24:01Z

On Fri, Jun 19, 2020 at 01:41:39PM -0700, Rick Lindsley wrote:
> On 6/19/20 8:38 AM, Tejun Heo wrote:
>
> > I don't have strong objections to the series but the rationales don't seem
> > particularly strong. It's solving a suspected problem but only half way. It
> > isn't clear whether this can be the long term solution for the problem
> > machine and whether it will benefit anyone else in a meaningful way either.
>
> I don't understand your statement about solving the problem halfway. Could
> you elaborate?

Spending 5 minutes during boot creating sysfs objects doesn't seem like a
particularly good solution and I don't know whether anyone else would
experience similar issues. Again, not necessarily against improving the
scalability of kernfs code but the use case seems a bit out there.

> > I think Greg already asked this but how are the 100,000+ memory objects
> > used? Is that justified in the first place?
>
> They are used for hotplugging and partitioning memory. The size of the
> segments (and thus the number of them) is dictated by the underlying
> hardware.

This sounds so bad. There gotta be a better interface for that, right?

Thanks.

--
tejun