The kernel's sched_setattr interface allows for more control over a processes
scheduling attributes as the previously used sched_setscheduler interface.
Using sched_setattr is also the prerequisite for support of utilization
clamping (UCLAMP [1], see #26705) and allows to set sched_runtime. The latter,
sched_runtime, will probably become a relevant scheduling parameter of the
EEVDF scheduler [2, 3], and therefore will not only apply to processes
scheduled via SCHED_DEADLINE, but also for processes scheduled via
SCHED_OTHER/SCHED_BATCH (i.e., most processes).
1: https://docs.kernel.org/next/scheduler/sched-util-clamp.html
2: https://lwn.net/Articles/969062/
3: https://lwn.net/ml/linux-kernel/20240405110010.934104715@infradead.org/
The construct is a POSIX invention, but it's just so useful, let's also
define it in EFI mode, so that we can use similar constructs in EFI mode
and userspace.
- introduce or rename usual enum values _MAX and _INVALID,
- introduce and use string table lookup functions,
- split out implementation of get_color_mode() to _impl(),
- add tests for get_color_mode().
This also
- merges basic/linux and shared/linux,
- moves BPF_JUMP_A() to basic/missing_bpf.h,
- copies from usrspace kernel headers directory generated by 'make headers',
rather than copying from kernel tree,
- copies const.h into our tree to reduce change in ethtool.h,
- copies auto_fs.h into our tree to reduce change in auto_dev-ioctl.h.
Builds with kernels headers < 4.14 fail with:
../src/shared/loop-util.c: In function ‘loop_configure_fallback’:
../src/shared/loop-util.c:237:31: error: ‘LOOP_SET_BLOCK_SIZE’ undeclared (first use in this function); did you mean ‘LOOP_SET_DIRECT_IO’?
if (ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) c->block_size) < 0)
^~~~~~~~~~~~~~~~~~~
LOOP_SET_DIRECT_IO
Fixes: https://github.com/systemd/systemd/issues/33341
Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>
Besides internal comparisons, the inode number of pidfds
might be interesting directly to users, too. In the future
this field should also be exposed, so that it can serve as
a unique identifier of a process (but only for display,
as there's no method to map this back to a pid or pidfd).
Also, make sure the NUL byte iovec becomes an exported constant too.
This is better than the previous situation where this was a macro
resolving to a compount expression, since the lifetime of the expression
is limited to its invoking scope. By turning this into a proper variable
the lifetime becomes unbounded, which makes it easier to use in various
scenarios, such as "if" blocks.
