diff options
Diffstat (limited to 'man2/ioprio_set.2')
| -rw-r--r-- | man2/ioprio_set.2 | 36 |
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 |