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diff --git a/sys-utils/chmem.8 b/sys-utils/chmem.8 new file mode 100644 index 0000000..8a3b34d --- /dev/null +++ b/sys-utils/chmem.8 @@ -0,0 +1,114 @@ +.TH CHMEM 8 "October 2016" "util-linux" "System Administration" +.SH NAME +chmem \- configure memory +.SH SYNOPSIS +.B chmem +.RB [ \-h "] [" \-V "] [" \-v "] [" \-e | \-d "]" +[\fISIZE\fP|\fIRANGE\fP|\fB\-b\fP \fIBLOCKRANGE\fP] +[-z ZONE] +.SH DESCRIPTION +The chmem command sets a particular size or range of memory online or offline. +. +.IP "\(hy" 2 +Specify \fISIZE\fP as <size>[m|M|g|G]. With m or M, <size> specifies the memory +size in MiB (1024 x 1024 bytes). With g or G, <size> specifies the memory size +in GiB (1024 x 1024 x 1024 bytes). The default unit is MiB. +. +.IP "\(hy" 2 +Specify \fIRANGE\fP in the form 0x<start>-0x<end> as shown in the output of the +\fBlsmem\fP command. <start> is the hexadecimal address of the first byte and <end> +is the hexadecimal address of the last byte in the memory range. +. +.IP "\(hy" 2 +Specify \fIBLOCKRANGE\fP in the form <first>-<last> or <block> as shown in the +output of the \fBlsmem\fP command. <first> is the number of the first memory block +and <last> is the number of the last memory block in the memory +range. Alternatively a single block can be specified. \fIBLOCKRANGE\fP requires +the \fB--blocks\fP option. +. +.IP "\(hy" 2 +Specify \fIZONE\fP as the name of a memory zone, as shown in the output of the +\fBlsmem -o +ZONES\fP command. The output shows one or more valid memory zones +for each memory range. If multiple zones are shown, then the memory range +currently belongs to the first zone. By default, chmem will set memory online +to the zone Movable, if this is among the valid zones. This default can be +changed by specifying the \fB--zone\fP option with another valid zone. +For memory ballooning, it is recommended to select the zone Movable for memory +online and offline, if possible. Memory in this zone is much more likely to be +able to be offlined again, but it cannot be used for arbitrary kernel +allocations, only for migratable pages (e.g. anonymous and page cache pages). +Use the \fB\-\-help\fR option to see all available zones. +. +.PP +\fISIZE\fP and \fIRANGE\fP must be aligned to the Linux memory block size, as +shown in the output of the \fBlsmem\fP command. + +Setting memory online can fail for various reasons. On virtualized systems it +can fail if the hypervisor does not have enough memory left, for example +because memory was overcommitted. Setting memory offline can fail if Linux +cannot free the memory. If only part of the requested memory can be set online +or offline, a message tells you how much memory was set online or offline +instead of the requested amount. + +When setting memory online \fBchmem\fP starts with the lowest memory block +numbers. When setting memory offline \fBchmem\fP starts with the highest memory +block numbers. +.SH OPTIONS +.TP +.BR \-b ", " \-\-blocks +Use a \fIBLOCKRANGE\fP parameter instead of \fIRANGE\fP or \fISIZE\fP for the +\fB--enable\fP and \fB--disable\fP options. +.TP +.BR \-d ", " \-\-disable +Set the specified \fIRANGE\fP, \fISIZE\fP, or \fIBLOCKRANGE\fP of memory offline. +.TP +.BR \-e ", " \-\-enable +Set the specified \fIRANGE\fP, \fISIZE\fP, or \fIBLOCKRANGE\fP of memory online. +.TP +.BR \-z ", " \-\-zone +Select the memory \fIZONE\fP where to set the specified \fIRANGE\fP, \fISIZE\fP, +or \fIBLOCKRANGE\fP of memory online or offline. By default, memory will be set +online to the zone Movable, if possible. +.TP +.BR \-h ", " \-\-help +Print a short help text, then exit. +.TP +.BR \-v ", " \-\-verbose +Verbose mode. Causes \fBchmem\fP to print debugging messages about it's +progress. +.TP +.BR \-V ", " \-\-version +Print the version number, then exit. +.SH RETURN CODES +.B chmem +has the following return codes: +.TP +.B 0 +success +.TP +.B 1 +failure +.TP +.B 64 +partial success +.SH EXAMPLES +.TP +.B chmem --enable 1024 +This command requests 1024 MiB of memory to be set online. +.TP +.B chmem -e 2g +This command requests 2 GiB of memory to be set online. +.TP +.B chmem --disable 0x00000000e4000000-0x00000000f3ffffff +This command requests the memory range starting with 0x00000000e4000000 +and ending with 0x00000000f3ffffff to be set offline. +.TP +.B chmem -b -d 10 +This command requests the memory block number 10 to be set offline. +.SH SEE ALSO +.BR lsmem (1) +.SH AVAILABILITY +The \fBchmem\fP command is part of the util-linux package and is available from +.UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ +Linux Kernel Archive +.UE . |