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| author | Matteo Croce <teknoraver@meta.com> | 2025-06-11 16:13:50 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2025-06-28 16:51:36 +0200 |
| commit | c4f63aada8b078ff95e2d21564b95ee437652449 (patch) | |
| tree | 4bd97ace51c5befcfee8eb313e21c1121292a610 | |
| parent | f2f77f09174fdcea4ca8088e2334fc3945be6291 (diff) | |
| download | man-pages-c4f63aada8b078ff95e2d21564b95ee437652449.tar.gz | |
man/man2/cachestat.2: Add page
The text was converted from the commit message in linux.git
cf264e1329fb (2023-06-09; "cachestat: implement cachestat syscall").
Link: <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>
Message-ID: <20250611141350.1829-1-technoboy85@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
| -rw-r--r-- | man/man2/cachestat.2 | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/man/man2/cachestat.2 b/man/man2/cachestat.2 new file mode 100644 index 0000000000..015401faf3 --- /dev/null +++ b/man/man2/cachestat.2 @@ -0,0 +1,112 @@ +.\" 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> +.P +.BI "int cachestat(unsigned int " fd ", struct cachestat_range *" cstat_range , +.BI " struct cachestat *" cstat ", unsigned int " flags ); +.fi +.P +.EX +.B struct cachestat_range { +.B " __u64 off;" +.B " __u64 len;" +.B }; +.P +.B struct cachestat { +.B " __u64 nr_cache;" +.B " __u64 nr_dirty;" +.B " __u64 nr_writeback;" +.B " __u64 nr_evicted;" +.B " __u64 nr_recently_evicted;" +.B }; +.EE +.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. +.P +The results are returned in a +.B cachestat +structure, pointed to by the +.I cstat +argument. +.P +The +.I .off +and +.I .len +fields must be non-negative. +If +.IR .len\~>\~0 , +the queried range is +.RI [ .off ,\~ .off+.len ]. +If +.IR len\~==\~0 , +the range is from +.I .off +to the end of the file. +.P +The +.I flags +argument is reserved for future use and must be set to +.BR 0 . +.P +Currently, +.B hugetlbfs +files are not supported. +.SH RETURN VALUE +On success, +.B cachestat() +returns 0. +On error, \-1 is returned, +and +.I errno +is set to indicate the error. +.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. +.SH STANDARDS +Linux. +.SH HISTORY +Linux 6.5. +.SH CAVEATS +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. |