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| author | Alejandro Colomar <alx@kernel.org> | 2024-04-26 15:06:49 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2024-05-02 01:24:19 +0200 |
| commit | dcde2f70372b49ec43efc5db864c9ff585d0a2dd (patch) | |
| tree | 78b9b7425130e4a5858e4c01a524d802423879ed /man/man2/alloc_hugepages.2 | |
| parent | 12aca537ce78a41bbcdaf485209691e10f8002d7 (diff) | |
| download | man-pages-dcde2f70372b49ec43efc5db864c9ff585d0a2dd.tar.gz | |
man/, share/mk/: Move man*/ to man/
This is a scripted change:
$ mkdir man/;
$ mv man* man/;
$ ln -st . man/man*;
$ find share/mk/ -type f \
| xargs grep -l '^MANDIR *:=' \
| xargs sed -i '/^MANDIR *:=/s,$,/man,';
$ find share/mk/dist/ -type f \
| xargs grep -l man \
| xargs sed -i 's,man%,man/%,g';
Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/>
Cc: Petr Vorel <pvorel@suse.cz>
Cc: Jakub Wilk <jwilk@jwilk.net>
Cc: Stefan Puiu <stefan.puiu@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Diffstat (limited to 'man/man2/alloc_hugepages.2')
| -rw-r--r-- | man/man2/alloc_hugepages.2 | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/man/man2/alloc_hugepages.2 b/man/man2/alloc_hugepages.2 new file mode 100644 index 0000000000..8e4b7ee1bd --- /dev/null +++ b/man/man2/alloc_hugepages.2 @@ -0,0 +1,135 @@ +.\" Copyright 2003 Andries E. Brouwer (aeb@cwi.nl) +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH alloc_hugepages 2 (date) "Linux man-pages (unreleased)" +.SH NAME +alloc_hugepages, free_hugepages \- allocate or free huge pages +.SH SYNOPSIS +.nf +.BI "void *syscall(SYS_alloc_hugepages, int " key ", void " addr [. len "], \ +size_t " len , +.BI " int " prot ", int " flag ); +.\" asmlinkage unsigned long sys_alloc_hugepages(int key, unsigned long addr, +.\" unsigned long len, int prot, int flag); +.BI "int syscall(SYS_free_hugepages, void *" addr ); +.\" asmlinkage int sys_free_hugepages(unsigned long addr); +.fi +.P +.IR Note : +glibc provides no wrappers for these system calls, +necessitating the use of +.BR syscall (2). +.SH DESCRIPTION +The system calls +.BR alloc_hugepages () +and +.BR free_hugepages () +were introduced in Linux 2.5.36 and removed again in Linux 2.5.54. +They existed only on i386 and ia64 (when built with +.BR CONFIG_HUGETLB_PAGE ). +In Linux 2.4.20, the syscall numbers exist, +but the calls fail with the error +.BR ENOSYS . +.P +On i386 the memory management hardware knows about ordinary pages (4\ KiB) +and huge pages (2 or 4\ MiB). +Similarly ia64 knows about huge pages of +several sizes. +These system calls serve to map huge pages into the +process's memory or to free them again. +Huge pages are locked into memory, and are not swapped. +.P +The +.I key +argument is an identifier. +When zero the pages are private, and +not inherited by children. +When positive the pages are shared with other applications using the same +.IR key , +and inherited by child processes. +.P +The +.I addr +argument of +.BR free_hugepages () +tells which page is being freed: it was the return value of a +call to +.BR alloc_hugepages (). +(The memory is first actually freed when all users have released it.) +The +.I addr +argument of +.BR alloc_hugepages () +is a hint, that the kernel may or may not follow. +Addresses must be properly aligned. +.P +The +.I len +argument is the length of the required segment. +It must be a multiple of the huge page size. +.P +The +.I prot +argument specifies the memory protection of the segment. +It is one of +.BR PROT_READ , +.BR PROT_WRITE , +.BR PROT_EXEC . +.P +The +.I flag +argument is ignored, unless +.I key +is positive. +In that case, if +.I flag +is +.BR IPC_CREAT , +then a new huge page segment is created when none +with the given key existed. +If this flag is not set, then +.B ENOENT +is returned when no segment with the given key exists. +.SH RETURN VALUE +On success, +.BR alloc_hugepages () +returns the allocated virtual address, and +.BR free_hugepages () +returns zero. +On error, \-1 is returned, and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B ENOSYS +The system call is not supported on this kernel. +.SH FILES +.TP +.I /proc/sys/vm/nr_hugepages +Number of configured hugetlb pages. +This can be read and written. +.TP +.I /proc/meminfo +Gives info on the number of configured hugetlb pages and on their size +in the three variables HugePages_Total, HugePages_Free, Hugepagesize. +.SH STANDARDS +Linux on Intel processors. +.SH HISTORY +These system calls are gone; +they existed only in Linux 2.5.36 through to Linux 2.5.54. +.SH NOTES +Now the hugetlbfs filesystem can be used instead. +Memory backed by huge pages (if the CPU supports them) is obtained by +using +.BR mmap (2) +to map files in this virtual filesystem. +.P +The maximal number of huge pages can be specified using the +.B hugepages= +boot parameter. +.\".P +.\" requires CONFIG_HUGETLB_PAGE (under "Processor type and features") +.\" and CONFIG_HUGETLBFS (under "Filesystems"). +.\" mount \-t hugetlbfs hugetlbfs /huge +.\" SHM_HUGETLB |