Re: [PATCH] man7, man2: document SCHED_EXT policy

[Cheng-Yang Chou <yphbchou0911@gmail.com>]

Hi Alejandro,

On Wed, Apr 22, 2026 at 06:02:49PM +0200, Alejandro Colomar wrote:
> > diff --git a/man/man2/sched_setattr.2 b/man/man2/sched_setattr.2
> > index 80a0ac726dcf..d60678f00e72 100644
> > --- a/man/man2/sched_setattr.2
> > +++ b/man/man2/sched_setattr.2
> > @@ -81,6 +81,10 @@ a deadline scheduling policy;
> >  see
> >  .BR sched (7)
> >  for details.
> > +.TP 14
> > +.B SCHED_EXT
> > +for extensible scheduling policies implemented via BPF
> > +(see \fBsched_ext\fR(7)).
> 
> Please follow the style within that manual page.  We avoid \f unless
> truly necessary.

Ack! This is my first time contributing here, so I'm still catching up
on the specific style rules.
> 
> >  .P
> >  The
> >  .I attr
> > @@ -95,7 +99,8 @@ struct sched_attr {
> >      u32 sched_policy;      /* Policy (SCHED_*) */
> >      u64 sched_flags;       /* Flags */
> >      s32 sched_nice;        /* Nice value (SCHED_OTHER,
> > -                              SCHED_BATCH) */
> > +                              SCHED_BATCH,
> > +                              SCHED_EXT) */
> 
> Why break the line?
> 
> >      u32 sched_priority;    /* Static priority (SCHED_FIFO,
> >                                SCHED_RR) */
> >      /* For SCHED_DEADLINE */
> > @@ -218,8 +223,10 @@ This field specifies the nice value to be set when specifying
> >  .I sched_policy
> >  as
> >  .B SCHED_OTHER
> > +,
> 
> What's the reason for this weird formatting of the source code?  At this
> point I wonder if this was generated by AI.

Yes, I used AI for the formatting, which I should disclose it, hence the
weird layout. Apologies for that. I believe the content is solid, but the
style needs adjusting. I'll send a v2. Thanks.

> Please take into account 'CONTRIBUTING.d/ai'.
> 
> > +.BR SCHED_BATCH ,
> >  or
> > -.BR SCHED_BATCH .
> > +.BR SCHED_EXT .
> >  The nice value is a number in the range \-20 (high priority)
> >  to +19 (low priority);
> >  see
> > diff --git a/man/man2/sched_setscheduler.2 b/man/man2/sched_setscheduler.2
> > index b4c35543e5bf..825eb7290ee7 100644
> > --- a/man/man2/sched_setscheduler.2
> > +++ b/man/man2/sched_setscheduler.2
> > @@ -67,6 +67,10 @@ and
> >  for running
> >  .I very
> >  low priority background jobs.
> > +.TP
> > +.B SCHED_EXT
> > +for extensible scheduling policies implemented via BPF
> > +(see \fBsched_ext\fR(7)).
> 
> Please check formatting.

Ack.

> >  .P
> >  For each of the above policies,
> >  .I param\->sched_priority
> > diff --git a/man/man7/sched.7 b/man/man7/sched.7
> > index 00926cd34ecf..2e73a4c716b9 100644
> > --- a/man/man7/sched.7
> > +++ b/man/man7/sched.7
> > @@ -116,6 +116,13 @@ and
> >  .BR sched_get_priority_max (2)
> >  to find the range of priorities supported for a particular policy.
> >  .P
> > +Since Linux 6.12, there is an extensible BPF scheduling policy
> > +.RB ( SCHED_EXT ),
> > +which allows for custom scheduling algorithms to be implemented as BPF
> > +programs.
> > +See
> > +.BR sched_ext (7).
> > +.P
> >  Conceptually,
> >  the scheduler maintains a list of runnable threads for each possible
> >  .I sched_priority
> > @@ -529,6 +536,12 @@ priority (lower even than a +19 nice value with the
> >  or
> >  .B SCHED_BATCH
> >  policies).
> > +.SS SCHED_EXT: Extensible BPF Scheduling
> > +Tasks with this policy are managed by an extensible scheduler class,
> > +which allows for custom scheduling algorithms to be implemented as
> > +BPF programs.
> > +See
> > +.BR sched_ext (7).
> >  .\"
> >  .SS Resetting scheduling policy for child processes
> >  Each thread has a reset-on-fork scheduling flag.
> > diff --git a/man/man7/sched_ext.7 b/man/man7/sched_ext.7
> > new file mode 100644
> > index 000000000000..7ea467e18b84
> > --- /dev/null
> > +++ b/man/man7/sched_ext.7
> > @@ -0,0 +1,100 @@
> > +.TH SCHED_EXT 7 2024-04-13 "Linux" "Linux Programmer's Manual"
> > +.SH NAME
> > +sched_ext \- Extensible BPF Scheduler Class
> > +.SH SYNOPSIS
> > +.B #include <linux/sched.h>
> > +.PP
> 
> The use of P and PP seems very inconsistent.
> 

Ack.

-- 
Cheers,
Cheng-Yang