Re: [RESEND RFC PATCH 0/3] Provide fast access to thread specific data

[Peter Oskolkov]

On Mon, Sep 13, 2021 at 10:36 AM Prakash Sangappa
<prakash.sangappa@xxxxxxxxxx> wrote:

[...]

> > This sounds, again, as if the kernel should be aware of the kind of
> > items being allocated; having a more generic mechanism of allocating
> > pinned memory for the userspace to use at its discretion would be more
> > generally useful, I think. But how then the kernel/system should be
> > protected from a buggy or malicious process trying to grab too much?
> >
> > One option would be to have a generic in-kernel mechanism for this,
> > but expose it to the userspace via domain-specific syscalls that do
> > the accounting you hint at. This sounds a bit like an over-engineered
> > solution, though…
>
>
> What will this pinned memory be used for in your use case,
> can you explain?

For userspace scheduling, to share thread/task state information
between the kernel and the userspace. This memory will be allocated
per task/thread; both the kernel and the userspace will write to the
shared memory, and these reads/writes will happen not only in the
memory regions belonging to the "current" task/thread, but also to
remote tasks/threads.

Somewhat detailed doc/rst is here:
https://lore.kernel.org/lkml/20210908184905.163787-5-posk@xxxxxxxxxx/