perfmonctl.2: Is it up to date?

perfmonctl.2: Is it up to date?

[Alejandro Colomar (man-pages)]

Hi Michael,

I haven't found any of the constants (PFM_*) used by this function in 
glibc.  Also not in the kernel, although in the kernel I found other 
PFM_* constants different from the ones in the manual page.

I checked that this page hasn't received any patches in a very long time 
(except for "Various pages" patches), so I suspect it may be out of date.

Also, does <perfmon.h> really exist?  I couldn't find it either.

Cheers,

Alex


-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: perfmonctl.2: Is it up to date?

[Michael Kerrisk (man-pages)]

Hello Alex,

On 4/23/21 10:31 PM, Alejandro Colomar (man-pages) wrote:
> Hi Michael,
> 
> I haven't found any of the constants (PFM_*) used by this function in 
> glibc.  Also not in the kernel, although in the kernel I found other 
> PFM_* constants different from the ones in the manual page.
> 
> I checked that this page hasn't received any patches in a very long time 
> (except for "Various pages" patches), so I suspect it may be out of date.
> 
> Also, does <perfmon.h> really exist?  I couldn't find it either.

It's certainly not up to date! In fact, this system call was removed
in Linux 5.10. I have applied the patch below.

Cheers,

Michael

diff --git a/man2/perfmonctl.2 b/man2/perfmonctl.2
index b376126a1..319712e6d 100644
--- a/man2/perfmonctl.2
+++ b/man2/perfmonctl.2
@@ -196,12 +196,18 @@ On error, \-1 is returned and
 is set to indicate the error.
 .SH VERSIONS
 .BR perfmonctl ()
-is available since Linux 2.4.
+was added in Linux 2.4;
+.\" commit ecf5b72d5f66af843f189dfe9ce31598c3e48ad7
+it was removed in Linux 5.10.
 .SH CONFORMING TO
 .BR perfmonctl ()
 is Linux-specific and is available only on the IA-64 architecture.
 .SH NOTES
-Glibc does not provide a wrapper for this system call; call it using
+This system call was broken for many years,
+and ultimately removed in Linux 5.10.
+.PP
+Glibc does not provide a wrapper for this system call;
+on kernels where it exists, call it using
 .BR syscall (2).
 .SH SEE ALSO
 .BR gprof (1)


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/