Re: [patch 00/11] rseq: Optimize exit to user space

[Mathieu Desnoyers]

On 2025-08-17 17:23, Thomas Gleixner wrote:
> On Thu, Aug 14 2025 at 00:08, Thomas Gleixner wrote:
> > On Wed, Aug 13 2025 at 15:36, Jens Axboe wrote:
> > > On 8/13/25 3:32 PM, Thomas Gleixner wrote:
> > > > Could you give it a test ride to see whether this makes a difference in
> > > > your environment?
> > >
> > > Yep, I'll give a spin.
> >
> > Appreciated.
>
> Please do not use the git branch I had in the cover letter. I did some
> more analysis of this and it's even worse than I thought. Use
>
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git rseq/wip
>
> instead.
>
> I've rewritten the whole pile by now and made it a real fast path
> without the TIF_NOTIFY horror show, unless the fast path, which runs
> _after_ the TIF work loop faults. So far that happens once for each
> fork() as that has to fault in the copy of the user space rseq region.

OK. I'll stop reviewing this version of the series and wait for an
updated version.

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com