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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
commit3af6d22bb3850ab2bac67287e3a3d3b0e32868e5 (patch)
tree3ee7a3ec64525911fa865bb984c86d997d855527 /man2/ioprio_set.2
parentAdding debian version 6.05.01-1. (diff)
downloadmanpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.tar.xz
manpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.zip
Merging upstream version 6.7.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man2/ioprio_set.2')
-rw-r--r--man2/ioprio_set.236
1 files changed, 18 insertions, 18 deletions
diff --git a/man2/ioprio_set.2 b/man2/ioprio_set.2
index 7770cbc..629d2df 100644
--- a/man2/ioprio_set.2
+++ b/man2/ioprio_set.2
@@ -7,7 +7,7 @@
.\" with various additions by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\"
-.TH ioprio_set 2 2023-04-03 "Linux man-pages 6.05.01"
+.TH ioprio_set 2 2023-10-31 "Linux man-pages 6.7"
.SH NAME
ioprio_get, ioprio_set \- get/set I/O scheduling class and priority
.SH LIBRARY
@@ -18,11 +18,11 @@ Standard C library
.BR "#include <linux/ioprio.h> " "/* Definition of " IOPRIO_* " constants */"
.BR "#include <sys/syscall.h> " "/* Definition of " SYS_* " constants */"
.B #include <unistd.h>
-.PP
+.P
.BI "int syscall(SYS_ioprio_get, int " which ", int " who );
.BI "int syscall(SYS_ioprio_set, int " which ", int " who ", int " ioprio );
.fi
-.PP
+.P
.IR Note :
glibc provides no wrappers for these system calls,
necessitating the use of
@@ -34,7 +34,7 @@ and
.BR ioprio_set ()
system calls get and set the I/O scheduling class and
priority of one or more threads.
-.PP
+.P
The
.I which
and
@@ -67,7 +67,7 @@ is a user ID identifying all of the processes that
have a matching real UID.
.\" FIXME . Need to document the behavior when 'who" is specified as 0
.\" See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652443
-.PP
+.P
If
.I which
is specified as
@@ -90,7 +90,7 @@ is the lowest)
or if it belongs to the same priority class as the other process but
has a higher priority level (a lower priority number means a
higher priority level).
-.PP
+.P
The
.I ioprio
argument given to
@@ -130,13 +130,13 @@ Given
value), this macro returns its priority
.RI ( data )
component.
-.PP
+.P
See the NOTES section for more
information on scheduling classes and priorities,
as well as the meaning of specifying
.I ioprio
as 0.
-.PP
+.P
I/O priorities are supported for reads and for synchronous
.RB ( O_DIRECT ,
.BR O_SYNC )
@@ -157,7 +157,7 @@ and
On error, \-1 is returned, and
.I errno
is set to indicate the error.
-.PP
+.P
On success,
.BR ioprio_set ()
returns 0.
@@ -211,12 +211,12 @@ is the one that is returned by
.BR gettid (2)
or
.BR clone (2).
-.PP
+.P
These system calls have an effect only when used
in conjunction with an I/O scheduler that supports I/O priorities.
As at kernel 2.6.17 the only such scheduler is the Completely Fair Queuing
(CFQ) I/O scheduler.
-.PP
+.P
If no I/O scheduler has been set for a thread,
then by default the I/O priority will follow the CPU nice value
.RB ( setpriority (2)).
@@ -233,20 +233,20 @@ as 0 can be used to reset to the default I/O scheduling behavior.
I/O schedulers are selected on a per-device basis via the special
file
.IR /sys/block/ device /queue/scheduler .
-.PP
+.P
One can view the current I/O scheduler via the
.I /sys
filesystem.
For example, the following command
displays a list of all schedulers currently loaded in the kernel:
-.PP
+.P
.in +4n
.EX
.RB "$" " cat /sys/block/sda/queue/scheduler"
noop anticipatory deadline [cfq]
.EE
.in
-.PP
+.P
The scheduler surrounded by brackets is the one actually
in use for the device
.RI ( sda
@@ -258,7 +258,7 @@ scheduler for the
.I sda
device to
.IR cfq :
-.PP
+.P
.in +4n
.EX
.RB "$" " su"
@@ -310,7 +310,7 @@ The idle class has no class data.
Attention is required when assigning this priority class to a process,
since it may become starved if higher priority processes are
constantly accessing the disk.
-.PP
+.P
Refer to the kernel source file
.I Documentation/block/ioprio.txt
for more information on the CFQ I/O Scheduler and an example program.
@@ -337,7 +337,7 @@ Up to Linux 2.6.24 also required
to set a very low priority
.RB ( IOPRIO_CLASS_IDLE ),
but since Linux 2.6.25, this is no longer required.
-.PP
+.P
A call to
.BR ioprio_set ()
must follow both rules, or the call will fail with the error
@@ -357,6 +357,6 @@ Suitable definitions can be found in
.BR open (2),
.BR capabilities (7),
.BR cgroups (7)
-.PP
+.P
.I Documentation/block/ioprio.txt
in the Linux kernel source tree