Re: [PATCH] memory hotplug disable boot option

KOSAKI Motohiro
2010-06-25T02:04:24Z

> Proposed patch to disable memory hotplug via a boot option,
> mem_hotplug=[on|off]. The patch only disables memory hotplug in that it
> prevents the creation of the memory sysfs directories for memory sections.
>
> This patch is meant to help alleviate very long boot times on systems with
> large memory (1+ TB) and many memory sections (10's of thousands).

Why making simple /sys file is so slowly? Couldn't we fix such performance
problem?

>
> Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
>
> ---
> drivers/base/memory.c | 33 +++++++++++++++++++++++++++++++++
> drivers/base/node.c | 3 +++
> include/linux/memory.h | 2 ++
> 3 files changed, 38 insertions(+)
>
> Index: linux-2.6/drivers/base/memory.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/memory.c 2010-06-23 15:07:03.000000000 -0500
> +++ linux-2.6/drivers/base/memory.c 2010-06-24 18:46:52.000000000 -0500
> @@ -29,6 +29,24 @@
>
> #define MEMORY_CLASS_NAME "memory"
>
> +static int mem_hp_enabled __read_mostly = 1;

please don't use 'hp' acronym. 'hotplug' is not so long word.

> +
> +static int __setup_memory_hotplug(char *option)
> +{
> + if (!strcmp(option, "off"))
> + mem_hp_enabled = 0;
> + else if (!strcmp(option, "on"))
> + mem_hp_enabled = 1;
> +
> + return 1;
> +}
> +__setup("mem_hotplug=", __setup_memory_hotplug);

no documentation on Documentation/kernel-parameters.txt?