From: Zhang Yanfei <[email protected]>
Since we already has config MOVABLE_NODE, and the boot option
movablenode is introduced as the boot-time switch to disable
the effects of CONFIG_MOVABLE_NODE=y when the system is booting.
So rename boot option movablenode to movable_node to match the
config MOVABLE_NODE. And also updates the description of MOVABLE_NODE
in mm/Kconfig and the description of movable_node in kernel doc.
Suggested-by: Ingo Molnar <[email protected]>
Signed-off-by: Zhang Yanfei <[email protected]>
---
Documentation/kernel-parameters.txt | 16 ++--------------
mm/Kconfig | 17 ++++++++++++-----
mm/memory_hotplug.c | 6 +++---
3 files changed, 17 insertions(+), 22 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a87e17e..953a533 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1773,20 +1773,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
that the amount of memory usable for all allocations
is not too small.
- movablenode [KNL,X86] This parameter enables/disables the
- kernel to arrange hotpluggable memory ranges recorded
- in ACPI SRAT(System Resource Affinity Table) as
- ZONE_MOVABLE. And these memory can be hot-removed when
- the system is up.
- By specifying this option, all the hotpluggable memory
- will be in ZONE_MOVABLE, which the kernel cannot use.
- This will cause NUMA performance down. For users who
- care about NUMA performance, just don't use it.
- If all the memory ranges in the system are hotpluggable,
- then the ones used by the kernel at early time, such as
- kernel code and data segments, initrd file and so on,
- won't be set as ZONE_MOVABLE, and won't be hotpluggable.
- Otherwise the kernel won't have enough memory to boot.
+ movable_node [KNL,X86] Boot-time switch to disable the effects
+ of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
diff --git a/mm/Kconfig b/mm/Kconfig
index ff6e820..8d4ebb0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -153,11 +153,18 @@ config MOVABLE_NODE
help
Allow a node to have only movable memory. Pages used by the kernel,
such as direct mapping pages cannot be migrated. So the corresponding
- memory device cannot be hotplugged. This option allows users to
- online all the memory of a node as movable memory so that the whole
- node can be hotplugged. Users who don't use the memory hotplug
- feature are fine with this option on since they don't online memory
- as movable.
+ memory device cannot be hotplugged. This option allows the following
+ two things:
+ - When the system is booting, node full of hotpluggable memory can
+ be arranged to have only movable memory so that the whole node can
+ be hotplugged. (need movable_node boot option specified).
+ - After the system is up, the option allows users to online all the
+ memory of a node as movable memory so that the whole node can be
+ hotplugged.
+
+ Users who don't use the memory hotplug feature are fine with this
+ option on since they don't specify movable_node boot option or they
+ don't online memory as movable.
Say Y here if you want to hotplug a whole node.
Say N here if you want kernel to use memory on all nodes evenly.
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b468f77..5e2aed9 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1424,7 +1424,7 @@ static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
}
#endif /* CONFIG_MOVABLE_NODE */
-static int __init cmdline_parse_movablenode(char *p)
+static int __init cmdline_parse_movable_node(char *p)
{
#ifdef CONFIG_MOVABLE_NODE
/*
@@ -1448,11 +1448,11 @@ static int __init cmdline_parse_movablenode(char *p)
*/
memblock_set_bottom_up(true);
#else
- pr_warn("movablenode option not supported");
+ pr_warn("movable_node option not supported");
#endif
return 0;
}
-early_param("movablenode", cmdline_parse_movablenode);
+early_param("movable_node", cmdline_parse_movable_node);
/* check which state of node_states will be changed when offline memory */
static void node_states_check_changes_offline(unsigned long nr_pages,
--
1.7.1
* Zhang Yanfei <[email protected]> wrote:
> @@ -153,11 +153,18 @@ config MOVABLE_NODE
> help
> Allow a node to have only movable memory. Pages used by the kernel,
> such as direct mapping pages cannot be migrated. So the corresponding
> + memory device cannot be hotplugged. This option allows the following
> + two things:
> + - When the system is booting, node full of hotpluggable memory can
> + be arranged to have only movable memory so that the whole node can
> + be hotplugged. (need movable_node boot option specified).
So this is _exactly_ what I complained about earlier: why is the
movable_node boot option needed to get that extra functionality? It's
clearly not just a drop-in substitute to CONFIG_MOVABLE_NODE but extends
its functionality, right?
Boot options are _very_ poor user interface. If you don't want to enable
it by default then turn this sub-functionality into
CONFIG_MOVABLE_NODE_AUTO and keep it default-off - but don't pretend that
this is only about CONFIG_MOVABLE_NODE alone - it isnt: as described above
the 'movable_node' is needed for the full functionality to be available!
Thanks,
Ingo
Hello Ingo,
On 10/01/2013 01:46 PM, Ingo Molnar wrote:
>
> * Zhang Yanfei <[email protected]> wrote:
>
>> @@ -153,11 +153,18 @@ config MOVABLE_NODE
>> help
>> Allow a node to have only movable memory. Pages used by the kernel,
>> such as direct mapping pages cannot be migrated. So the corresponding
>> + memory device cannot be hotplugged. This option allows the following
>> + two things:
>> + - When the system is booting, node full of hotpluggable memory can
>> + be arranged to have only movable memory so that the whole node can
>> + be hotplugged. (need movable_node boot option specified).
>
> So this is _exactly_ what I complained about earlier: why is the
> movable_node boot option needed to get that extra functionality? It's
> clearly not just a drop-in substitute to CONFIG_MOVABLE_NODE but extends
> its functionality, right?
Generally speaking, CONFIG_MOVABLE_NODE is used to allow a node to have
only movable memory. Firstly, we didn't support the functionality to support
boot-time configuration. That said, before this patchset, we only support
later hot-add node to have only movable memory but any node that is dectected
at boot-time cannot. So here is movable_node option, to protect the kernel
from using hotpluggable memory at boot-time and if a node is full of hotpluggable
memory, this node is arranged to have only movable memory and can be hot-removed
after the system is up.
>
> Boot options are _very_ poor user interface. If you don't want to enable
> it by default then turn this sub-functionality into
> CONFIG_MOVABLE_NODE_AUTO and keep it default-off - but don't pretend that
> this is only about CONFIG_MOVABLE_NODE alone - it isnt: as described above
> the 'movable_node' is needed for the full functionality to be available!
As explained above, we need the boot option to only disable boot-time
memory-hotplug configuration not the whole MOVABLE_NODE functionality.
Thanks
--
Thanks.
Zhang Yanfei