Corinna Vinschen wrote:
On Nov 29 18:48, Christian Franke wrote:
A very first attempt to let sched_setscheduler() do something possibly
useful.
This patch is on top of
Cygwin: setpriority, sched_setparam: add missing process access right
Looks quite nice. If you're confident this is ready for the main
branch, just give the word!
Yes, initial tests look good. Related documentation update attached.
From 7b422c55a120c523550efc3423f230630d082fac Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.fra...@t-online.de>
Date: Mon, 2 Dec 2024 18:27:22 +0100
Subject: [PATCH] Cygwin: doc: document sched_setpolicy(2) and priority mapping
Document the long standing mapping from nice or sched_priority
values to Windows priority classes and the new behavior of
sched_setpolicy(8).
Signed-off-by: Christian Franke <christian.fra...@t-online.de>
---
winsup/doc/posix.xml | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
diff --git a/winsup/doc/posix.xml b/winsup/doc/posix.xml
index 89056915b..436ab00a7 100644
--- a/winsup/doc/posix.xml
+++ b/winsup/doc/posix.xml
@@ -601,7 +601,7 @@ also IEEE Std 1003.1-2017 (POSIX.1-2017).</para>
nexttowardf
nexttowardl
nftw
- nice
+ nice (see <xref linkend="std-notes">chapter
"Implementation Notes"</xref>)
nl_langinfo
nl_langinfo_l
nrand48
@@ -818,8 +818,8 @@ also IEEE Std 1003.1-2017 (POSIX.1-2017).</para>
sched_getparam
sched_getscheduler
sched_rr_get_interval
- sched_setparam
- sched_setscheduler
+ sched_setparam (see <xref linkend="std-notes">chapter
"Implementation Notes"</xref>)
+ sched_setscheduler (see <xref linkend="std-notes">chapter
"Implementation Notes"</xref>)
sched_yield
seed48
seekdir
@@ -854,7 +854,7 @@ also IEEE Std 1003.1-2017 (POSIX.1-2017).</para>
setlogmask
setpgid
setpgrp
- setpriority
+ setpriority (see <xref linkend="std-notes">chapter
"Implementation Notes"</xref>)
setprotoent
setpwent
setregid
@@ -1769,6 +1769,32 @@ atomic either. Over-allocation with FALLOC_FL_KEEP_SIZE
is only
temporary on Windows until the last handle to the file is closed.
Over-allocation on sparse files is entirely ignored on Windows.</para>
+<para><function>sched_setpolicy</function> only emulates API behavior
+because Windows does not offer alternative scheduling policies.
+If <literal>SCHED_OTHER</literal> is selected, the Windows priority is
+set according to the nice value. If <literal>SCHED_FIFO</literal>
+or <literal>SCHED_RR</literal> is selected, the nice value is preserved
+and the Windows priority is set according to the
+<literal>sched_priority</literal> value.</para>
+
+<para><function>nice</function>, <function>setpriority</function>,
+<function>sched_setparam</function> and <function>sched_setpolicy</function>
+map the nice value (<literal>SCHED_OTHER</literal>) or the
+<literal>sched_priority</literal> (<literal>SCHED_FIFO</literal>,
+<literal>SCHED_RR</literal>) to Windows priority classes as follows:</para>
+<screen>
+ nice value sched_priority Windows priority class
+ 12...19 1....6 IDLE_PRIORITY_CLASS
+ 4...11 7...12 BELOW_NORMAL_PRIORITY_CLASS
+ -4....3 13...18 NORMAL_PRIORITY_CLASS
+ -12...-5 19...24 ABOVE_NORMAL_PRIORITY_CLASS
+ -13..-19 25...30 HIGH_PRIORITY_CLASS
+ -20 31...32 REALTIME_PRIORITY_CLASS
+</screen>
+The use of values which are mapped to the
+<literal>REALTIME_PRIORITY_CLASS</literal> require administrative
+privileges.
+
</sect1>
</chapter>
--
2.45.1
