--- v1
+++ v2
@@ -1,115 +1,82 @@
-Update the outdated information:
-- The PREEMPT_RT patch is merged. The patch continues to exist (as of
- now) but is not mandatory.
-- The patch can be still downloaded but most people use the git tree
- these days. Add a reference to it.
-- CONFIG_PREEMPT_DESKTOP was never thing as far as I remember. It was
- always CONFIG_PREEMPT and its description referred to "low latency
- desktop".
-- Within the PREEMPT-RT patch there was a brief window which introduced
- PREEMPT_RT_BASE and PREEMPT_RT_FULL. I am going to ignore this.
-- The introduction of PREEMPT_LAZY in 6.13 moved PREEMPT_RT from a
- preemption model to an option.
-- The mentioned wiki is deprecated. Update the URL to the new one.
-
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
- man/man7/sched.7 | 58 ++++++++++++++++++++++++++++++++++--------------
- 1 file changed, 41 insertions(+), 17 deletions(-)
+ man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const | 67 ++++++++++++++++++++
+ 1 file changed, 67 insertions(+)
+ create mode 100644 man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const
-diff --git a/man/man7/sched.7 b/man/man7/sched.7
-index 3299c21dc1ad8..5da631c310636 100644
---- a/man/man7/sched.7
-+++ b/man/man7/sched.7
-@@ -933,16 +933,12 @@ the following to modify the autogroup nice value for
- .EE
- .in
- .SS Real-time features in the mainline Linux kernel
--.\" FIXME . Probably this text will need some minor tweaking
--.\" ask Carsten Emde about this.
-+.\" The archaeologist knows about v2.6.9-mm1-V0.1-realtime-preempt
- Since Linux 2.6.18, Linux is gradually
- becoming equipped with real-time capabilities,
- most of which are derived from the former
- .I realtime\-preempt
- patch set.
--Until the patches have been completely merged into the
--mainline kernel,
--they must be installed to achieve the best real-time performance.
- These patches are named:
- .P
- .in +4n
-@@ -953,24 +949,52 @@ they must be installed to achieve the best real-time performance.
- .P
- and can be downloaded from
- .UR http://www.kernel.org\:/pub\:/linux\:/kernel\:/projects\:/rt/
-+.UE
-+or cloned from a git tree
-+.UR https://git.kernel.org\:/pub\:/scm\:/linux\:/kernel\:/git\:/rt\:/linux-stable-rt.git
- .UE .
-+The individual releases are maintained as long as
-+the matching LTS kernel is maintained.
- .P
--Without the patches and prior to their full inclusion into the mainline
--kernel, the kernel configuration offers only the three preemption classes
-+Since 6.12 it possible to enable the real-time preemption
-+without the need for any patches.
-+The
-+.I realtime\-patch
-+continues to exist and contains support
-+for not yet integrated architectures,
-+drivers and features that are in development.
+diff --git a/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const b/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const
+new file mode 100644
+index 0000000000000..1605c18c6985b
+--- /dev/null
++++ b/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const
+@@ -0,0 +1,67 @@
++.\" Copyright, the authors of the Linux man-pages project
++.\"
++.\" SPDX-License-Identifier: Linux-man-pages-copyleft
++.\"
++.TH PR_FUTEX_HASH_SET_SLOTS 2const (date) "Linux man-pages (unreleased)"
++.SH NAME
++PR_FUTEX_HASH_SET_SLOTS
++\-
++set the size of the private hash
++.SH LIBRARY
++Standard C library
++.RI ( libc ,\~ \-lc )
++.SH SYNOPSIS
++.nf
++.BR "#include <linux/prctl.h>" " /* Definition of " PR_* " constants */"
++.B #include <sys/prctl.h>
+.P
-+Since 6.13 real-time becomes an option
-+and not a preemption model.
-+With this change,
-+the following preemption models are available:
- .BR CONFIG_PREEMPT_NONE ,
- .BR CONFIG_PREEMPT_VOLUNTARY ,
-+.BR CONFIG_PREEMPT ,
- and
--.B CONFIG_PREEMPT_DESKTOP
--which respectively provide no, some, and considerable
--reduction of the worst-case scheduling latency.
--.P
--With the patches applied or after their full inclusion into the mainline
--kernel, the additional configuration item
-+.BR CONFIG_PREEMPT_LAZY .
-+The real-time capabilities can be enabled with the option
- .B CONFIG_PREEMPT_RT
--becomes available.
--If this is selected, Linux is transformed into a regular
-+and the preemption model be set to either
-+.B CONFIG_PREEMPT
-+or
-+.BR CONFIG_PREEMPT_LAZY .
-+The latter model is less eager to preempt
-+.B SCHED_NORMAL
-+tasks in an attempt to reduce lock holder preemption.
-+It does not affect real-time tasks.
-+.P
-+With
-+.B CONFIG_PREEMPT_RT
-+enabled,
-+Linux is transformed into a regular
- real-time operating system.
--The FIFO and RR scheduling policies are then used to run a thread
-+The
-+.BR SCHED_FIFO ,
-+.BR SCHED_RR ,
-+and
-+.B SCHED_DL
-+scheduling policies are then used to run a thread
- with true real-time priority and a minimum worst-case scheduling latency.
- .SH NOTES
- The
-@@ -1032,5 +1056,5 @@ and
- .I \%Documentation/\:scheduler/\:sched\-nice\-design\:.txt
- .P
- Worth looking at:
--.UR http://rt.wiki.kernel.org/\:index.php
-+.UR https://wiki.linuxfoundation.org/\:realtime/\:start
- .UE
++.B int prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS,
++.BI " unsigned long " size ", unsigned long " flags ");
++.fi
++.SH DESCRIPTION
++Set the number of slots to use for the private hash.
++.TP
++.I size
++Specify the size of private hash to allocate.
++.RS
++.TP
++.I 0
++Use the global hash.
++This is the behaviour used before 6.17.
++.TP
++.I >0
++Specify the number of slots to allocate.
++The value must be power of two, and the lowest possible value is 2.
++The upper limit depends on the available memory in the system.
++Each slot requires 64 bytes of memory.
++Kernels compiled with
++.I CONFIG_PROVE_LOCKING
++will consume more than that.
++.RE
++.TP
++.I flags
++.RS
++The argument must be 0.
++.SH RETURN VALUE
++On success,
++0 is returned.
++On error, \-1 is returned, and
++.I errno
++is set to indicate the error.
++.SH ERRORS
++.TP
++.B EINVAL
++An argument is invalid.
++.TP
++.B ENOMEM
++Failed to allocate memory.
++.TP
++.B EBUSY
++The global hash is in use and can not be changed.
++.SH STANDARDS
++Linux.
++.SH HISTORY
++Linux 6.17.
++.SH SEE ALSO
++.BR prctl (2),
++.BR PR_FUTEX_HASH (2const)
--
2.51.0