Um exemplo de uma modificação numa área central derivada de uma necessidade
específica: melhorar a performance de uprobes

On Thu, Aug 15, 2024, 4:07 PM Mateusz Guzik <mjguzik@gmail.com> wrote:

> On Thu, Aug 15, 2024 at 8:58 PM Jann Horn <jannh@google.com> wrote:
> > Stupid question: Is this uprobe stuff actually such a hot codepath
> > that it makes sense to optimize it to be faster than the page fault
> > path?
> >
>
> That's what I implicitly asked, hoping a down_read on vma would do it,
> but Andrii claims multiple parallel lookups on the same vma are a
> problem.
>
> Even so, I suspect something *simple* is doable here which avoids any
> writes to vmas and does not need the mm-wide sequence counter. It may
> be requirements are lax enough that merely observing some state is the
> same before and after uprobe lookup will be sufficient, or maybe some
> other hackery is viable without messing with fences in
> vma_start_write.
> --
> Mateusz Guzik <mjguzik gmail.com>
>
>