Messages in this thread | | | Subject | Re: [PATCH] io_submit.2: Add IOCB_FLAG_IOPRIO | From | "Michael Kerrisk (man-opages)" <> | Date | Mon, 13 Aug 2018 18:39:57 +0200 |
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Hello Adam,
On 07/13/2018 10:58 PM, adam.manzanares@wdc.com wrote: > From: Adam Manzanares <adam.manzanares@wdc.com> > > The newly added IOCB_FLAG_IOPRIO aio_flag introduces > new behaviors and return values. > > The details of this new feature are posted here: > https://lkml.org/lkml/2018/5/22/809
Thanks for this patch. I've applied it, but I have a question below about a detail that probably needs fixing.
> Signed-off-by: Adam Manzanares <adam.manzanares@wdc.com> > --- > man2/io_submit.2 | 34 +++++++++++++++++++++++++++------- > 1 file changed, 27 insertions(+), 7 deletions(-) > > diff --git a/man2/io_submit.2 b/man2/io_submit.2 > index d17e3122a..15e1ecdea 100644 > --- a/man2/io_submit.2 > +++ b/man2/io_submit.2 > @@ -164,14 +164,26 @@ This is the size of the buffer pointed to by > This is the file offset at which the I/O operation is to be performed. > .TP > .I aio_flags > -This is the flag to be passed iocb structure. > -The only valid value is > -.BR IOCB_FLAG_RESFD , > -which indicates that the asynchronous I/O control must signal the file > +This is the set of flags associated with the iocb structure. > +The valid values are: > +.RS > +.TP > +.BR IOCB_FLAG_RESFD > +Asynchronous I/O control must signal the file > descriptor mentioned in > .I aio_resfd > upon completion. > .TP > +.BR IOCB_FLAG_IOPRIO " (since Linux 4.18)" > +.\" commit d9a08a9e616beeccdbd0e7262b7225ffdfa49e92 > +Interpret the > +.I aio_reqprio > +field as an > +.B IOPRIO_VALUE > +as defined by > +.IR linux/ioprio.h. > +.RE > +.TP > .I aio_resfd > The file descriptor to signal in the event of asynchronous I/O completion. > .SH RETURN VALUE > @@ -196,13 +208,21 @@ The AIO context specified by \fIctx_id\fP is invalid. > \fInr\fP is less than 0. > The \fIiocb\fP at > .I *iocbpp[0] > -is not properly initialized, > -or the operation specified is invalid for the file descriptor > -in the \fIiocb\fP. > +is not properly initialized, the operation specified is invalid for the file > +descriptor in the \fIiocb\fP, or the value in the > +.I aio_reqprio > +field is invalid. > .TP > .B ENOSYS > .BR io_submit () > is not implemented on this architecture. > +.TP > +.B EPERM > +The aio_reqprio field is set with the class > +.B IOPRIO_CLASS_RT > +, but the submitting context does not have the
What does "submitting context" mean? Threads/tasks/processes have capabilities. Can you rephrase in terms of processes/threads?
Thanks,
Michael
> +.B CAP_SYS_ADMIN > +privilege. > .SH VERSIONS > .PP > The asynchronous I/O system calls first appeared in Linux 2.5. >
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