Re: [PATCH v2] memory-hotplug: add sysfs zones_online_to attribute
From: Zhang Zhen
Date: Sun Aug 24 2014 - 21:55:48 EST
On 2014/8/23 6:16, Andrew Morton wrote:
> On Mon, 18 Aug 2014 11:25:36 +0800 Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx> wrote:
>> On 2014/8/16 5:37, Toshi Kani wrote:
>>> On Wed, 2014-08-13 at 12:10 +0800, Zhang Zhen wrote:
>>>> Currently memory-hotplug has two limits:
>>>> 1. If the memory block is in ZONE_NORMAL, you can change it to
>>>> ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
>>>> 2. If the memory block is in ZONE_MOVABLE, you can change it to
>>>> ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.
>>>> With this patch, we can easy to know a memory block can be onlined to
>>>> which zone, and don't need to know the above two limits.
>>>> Updated the related Documentation.
>>>> Change v1 -> v2:
>>>> - optimize the implementation following Dave Hansen's suggestion
>>>> Signed-off-by: Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
>>>> Documentation/ABI/testing/sysfs-devices-memory | 8 ++++
>>>> Documentation/memory-hotplug.txt | 4 +-
>>>> drivers/base/memory.c | 62 ++++++++++++++++++++++++++
>>>> include/linux/memory_hotplug.h | 1 +
>>>> mm/memory_hotplug.c | 2 +-
>>>> 5 files changed, 75 insertions(+), 2 deletions(-)
>>>> diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
>>>> index 7405de2..2b2a1d7 100644
>>>> --- a/Documentation/ABI/testing/sysfs-devices-memory
>>>> +++ b/Documentation/ABI/testing/sysfs-devices-memory
>>>> @@ -61,6 +61,14 @@ Users: hotplug memory remove tools
>>>> +What: /sys/devices/system/memory/memoryX/zones_online_to
>>> I think this name is a bit confusing. How about "valid_online_types"?
>> Thanks for your suggestion.
>> This patch has been added to -mm tree.
>> If most people think so, i would like to modify the interface name.
>> If not, let's leave it as it is.
> Yes, the name could be better. Do we actually need "online" in there?
> How about "valid_zones"?
Ok, i will change it to valid_zones.
> Also, it's not really clear to me why we need this sysfs file at all.
> Do people really read sysfs files, make onlining decisions and manually
> type in commands? Or is this stuff all automated? If the latter then
> the script can take care of all this? For example, attempt to online
> the memory into the desired zone and report failure if that didn't
Just like Dave Hansen says, the scripts should be changed when we add a new
zone type. And ZONE_MOVABLE may be missed by the scripts writer.
> IOW, please update the changelog to show
> a) example output from
> /sys/devices/system/memory/memoryX/whatever-we-call-it and
> b) example use-cases which help reviewers understand why this
> feature will be valuable to users.
Sorry, this patch has been added to -next tree. I can't modify the changelog.
> Also, please do address the error which Yasuaki Ishimatsu identified.
Yeah, i have been waiting for http://ozlabs.org/~akpm/mmots/broken-out/memory-hotplug-add-sysfs-zones_online_to-attribute-fix-2.patch
added to -mm tree.
So i can send a patch based on -mm tree to address the error which Yasuaki Ishimatsu identified.
Otherwise, conflicts may occur.
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