* Re: [PATCH v2] man/man2/cachestat.2: add a man page for cachestat()
2025-05-26 17:43 [PATCH v2] man/man2/cachestat.2: add a man page for cachestat() Matteo Croce
@ 2025-05-30 9:34 ` Alejandro Colomar
0 siblings, 0 replies; 2+ messages in thread
From: Alejandro Colomar @ 2025-05-30 9:34 UTC (permalink / raw)
To: Matteo Croce; +Cc: linux-man, Nhat Pham, Johannes Weiner, Matteo Croce
[-- Attachment #1: Type: text/plain, Size: 4499 bytes --]
Hi Matteo,
On Mon, May 26, 2025 at 07:43:08PM +0200, Matteo Croce wrote:
> From: Matteo Croce <teknoraver@meta.com>
>
> Add a missing man page for cachestat().
> The text was converted from the commit message:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cf264e1329fb0307e044f7675849f9f38b44c11a
>
> Signed-off-by: Nhat Pham <nphamcs@gmail.com>
> Signed-off-by: Matteo Croce <teknoraver@meta.com>
> ---
> man/man2/cachestat.2 | 106 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 106 insertions(+)
> create mode 100644 man/man2/cachestat.2
>
> diff --git a/man/man2/cachestat.2 b/man/man2/cachestat.2
> new file mode 100644
> index 000000000..e7f60d935
> --- /dev/null
> +++ b/man/man2/cachestat.2
> @@ -0,0 +1,106 @@
> +.\" Copyright, the authors of the Linux man-pages project
> +.\"
> +.\" SPDX-License-Identifier: Linux-man-pages-copyleft
> +.\"
> +.TH cachestat 2 (date) "Linux man-pages (unreleased)"
> +.SH NAME
> +cachestat \- query the page cache statistics of a file
> +.SH SYNOPSIS
> +.nf
> +.B #include <sys/mman.h>
> +.PP
s/PP/P/g
> +.B struct cachestat_range {
> +.BR " __u64 off;"
Since these lines only have 1 argument, s/BR/B/g.
See groff_man(7):
.B [text]
Set text in bold. If no argument is given, a one‐line in‐
put trap is planted; text on the next line, which can be
further formatted with a macro, is set in bold.
.BR bold‐text roman‐text ...
Set each argument in bold and roman, alternately.
> +.BR " __u64 len;"
> +.RE
This RE is spurious.
> +.B };
> +.PP
> +.B struct cachestat {
> +.BR " __u64 nr_cache;"
> +.BR " __u64 nr_dirty;"
> +.BR " __u64 nr_writeback;"
> +.BR " __u64 nr_evicted;"
> +.BR " __u64 nr_recently_evicted;"
> +.B };
> +.PP
> +.BI "int cachestat(unsigned int " fd ", struct cachestat_range *" cstat_range ","
> +.br
This br is spurious.
> +.BI " struct cachestat *" cstat ", unsigned int " flags ");"
> +.nf
> +.SH DESCRIPTION
> +.B cachestat()
> +queries the number of cached pages, dirty pages,
> +pages marked for writeback, evicted pages,
> +and recently evicted pages in the byte range specified by
> +.I .off
> +and
> +.I .len
> +in the
> +.B cachestat_range
> +structure.
> +.P
> +An evicted page is one that was previously in the page cache
> +but has since been evicted.
> +A page is considered recently evicted if its reentry into the cache
> +would indicate active usage under memory pressure.
> +.PP
> +The results are returned in a
> +.B cachestat
> +structure, pointed to by the
> +.I cstat
> +argument.
> +.PP
> +The
> +.I .off
> +and
> +.I .len
> +fields must be non-negative. If
s/\. /.\n/
> +.I .len > 0
> +, the queried range is
The comma should go in the previous line. Otherwise, it creates a
spurious space.
.IR .len\~>\~0 ,
> +.RI [ .off ,\~ .off+.len ]
> +. If
> +.IR len\~==\~0 ,
> +the range is from
> +.I .off
> +to the end of the file.
> +.PP
> +The
> +.I flags
> +argument is reserved for future use and must be set to
> +.BR 0 .
> +.
> +.PP
> +Currently,
> +.B hugetlbfs
> +files are not supported.
> +.PP
> +Note that the status of a page may change after
> +.B cachestat()
> +retrieves it but before the values are returned to the application;
> +thus, the values may be slightly outdated.
I'd move the paragraph from above to a CAVEATS section (see
man-pages(7)).
> +.SH RETURN VALUE
> +On success,
> +.B cachestat()
> +returns 0. On error, \-1 is returned and
s/\. /.\n/
s/ and/,\nand/
> +.I errno
> +is set appropriately.
> +.SH ERRORS
> +.TP
> +.B EFAULT
> +.I cstat
> +or
> +.I cstat_range
> +point to an invalid address.
> +.TP
> +.B EINVAL
> +Invalid
> +.I flags
> +value.
> +.TP
> +.B EBADF
> +Invalid file descriptor.
> +.TP
> +.B EOPNOTSUPP
> +The file descriptor refers to a
> +.B hugetlbfs
> +file, which is unsupported.
Please add STANDARDS and HISTORY sections. You can have a look at
membarrier(2) for this:
$ man -w membarrier | xargs mansect '(STANDARDS|HISTORY)' | tail -n+3;
.SH STANDARDS
Linux.
.SH HISTORY
Linux 4.3.
.P
Before Linux 5.10, the prototype was:
.P
.in +4n
.EX
.BI "int membarrier(int " cmd ", int " flags );
.EE
.in
> --
> 2.49.0
Have a lovely day!
Alex
--
<https://www.alejandro-colomar.es/>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 2+ messages in thread