From: Colin Patrick McCabe <cmccabe@xxxxxxxxxxxxxx> Signed-off-by: Colin McCabe <cmccabe@xxxxxxxxxxxxxx> --- man2/ioprio_set.2 | 25 ++++++++++++++++++++++--- 1 files changed, 22 insertions(+), 3 deletions(-) diff --git a/man2/ioprio_set.2 b/man2/ioprio_set.2 index 37b4dc1..807c655 100644 --- a/man2/ioprio_set.2 +++ b/man2/ioprio_set.2 @@ -36,13 +36,13 @@ The and .BR ioprio_set () system calls respectively get and set the I/O scheduling class and -priority of one or more processes. +priority of one or more threads. The .I which and .I who -arguments identify the process(es) on which the system +arguments identify the thead(s) on which the system calls operate. The .I which @@ -52,7 +52,7 @@ is interpreted, and has one of the following values: .TP .B IOPRIO_WHO_PROCESS .I who -is a process ID identifying a single process. +is a process ID or thread ID identifying a single process or thread. .TP .B IOPRIO_WHO_PGRP .I who @@ -186,6 +186,25 @@ kernel 2.6.13. .SH "CONFORMING TO" These system calls are Linux-specific. .SH NOTES +Two or more processes or threads can share an I/O context. This will be the +case when +.BR clone (2) +was called with the +.B CLONE_IO +flag. + +However, by default, the distinct threads of a process will +.B not +share the same I/O context. This means that if you want to change the I/O +priority of all threads in a process, you may need to call +.BR ioprio_set() +on all of the threads. The thread ID you would need for this operation is that +which is returned by +.BR gettid(), +not +.BR pthread_self() +or another userspace API. + Glibc does not provide wrapper for these system calls; call them using .BR syscall (2). -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
