Re: SCHED_DEADLINE as user

On 21/08/18 00:45, Tim Blechmann wrote:

[...]

apart from that, i'm only missing two features:

* using SCHED_DEADLINE from user applications is kind of a showstopper
for me

Right. Would you be up for continuing experimenting with DEADLINE (while
we get our heads around removing this constraint) by - ugly hack warning
- removing the check at

https://elixir.bootlin.com/linux/latest/source/kernel/sched/core.c#L4216

?

I guess it would be good if you could provide even more feedback than
you already did, so that we can plan ahead what needs fixing/changing or
implementing.

BTW, thanks a lot already for this discussion! :-)

* a nicer glibc wrapper, that allows me to use pthreads rather than
using `syscall`: it's all pretty easy to obtain the `tid` for a calling
thread (gettid), but it seems to be impossible to obtain the `tid` from
 `pthread_t` without some hacks which are way too dirty to share in
public ...

Indeed. We have been basically relying on

https://github.com/scheduler-tools/rt-app/tree/master/libdl

so far. But, I guess it's time - it has been time for a while - that we
reach glibc guys and try to understand why this is not yet all in the
standard libraries.

On 21/08/18 09:38, Juri Lelli wrote:

On 21/08/18 00:45, Tim Blechmann wrote:

[...]

quoted

apart from that, i'm only missing two features:

* using SCHED_DEADLINE from user applications is kind of a showstopper
for me

Right. Would you be up for continuing experimenting with DEADLINE (while
we get our heads around removing this constraint) by - ugly hack warning
- removing the check at

https://elixir.bootlin.com/linux/latest/source/kernel/sched/core.c#L4216

?

I guess it would be good if you could provide even more feedback than
you already did, so that we can plan ahead what needs fixing/changing or
implementing.

BTW, thanks a lot already for this discussion! :-)

quoted

* a nicer glibc wrapper, that allows me to use pthreads rather than
using `syscall`: it's all pretty easy to obtain the `tid` for a calling
thread (gettid), but it seems to be impossible to obtain the `tid` from
 `pthread_t` without some hacks which are way too dirty to share in
public ...

Indeed. We have been basically relying on

https://github.com/scheduler-tools/rt-app/tree/master/libdl

so far. But, I guess it's time - it has been time for a while - that we
reach glibc guys and try to understand why this is not yet all in the
standard libraries.

FYI, I added both points to the list of known issues. Feel free to add
details.

https://github.com/jlelli/linux/issues

Best,

- Juri