Re: [RFC 16/16] lpfc: vmid: Introducing vmid in io path.

Tejun Heo
2020-08-06T18:49:25Z

On Thu, Aug 06, 2020 at 08:39:26PM +0200, Paolo Bonzini wrote:
> On 06/08/20 16:59, Tejun Heo wrote:
> >> If I understand correctly, your only objection is that you'd rather not
> >> have it specified with a file under /sys/kernel/cgroup, and instead you
> >> would prefer to have it implemented as a ioctl for a magic file
> >> somewhere else in sysfs? I don't think there is any precedent for this,
> >> and I'm not even sure where that sysfs file would be.
> > It just doesn't fit in the cgroupfs. I don't know where it should go for
> > this specific case. That's for you guys to figure out. There are multiple
> > precedences - e.g. how perf or bpf hooks into cgroup and others that I can't
> > remember off the top of my head.
>
> perf and bpf have file descriptors, system calls and data structures of
> their own, here there is simply none: it's just an array of chars. Can
> you explain _why_ it doesn't fit in the cgroupfs?

What's the hierarchical or delegation behavior? Why do the vast majority of
people who don't have the hardware or feature need to see it? We can argue
but I can pretty much guarantee that the conclusion is gonna be the same and
it's gonna be a waste of time and energy for both of us.

Thanks.

--
tejun