[PATCH 0/3] powerpc/pseries: Manage single copy of ibm, dynamic-memory

Michael Ellerman mpe at ellerman.id.au
Thu Feb 2 17:08:59 AEDT 2017

Nathan Fontenot <nfont at linux.vnet.ibm.com> writes:

> The ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory property
> of the device-tree can be fairly big on systems with a large amount
> of memory. A system with 1 TB of memory (256 MB LMBs) the property
> size is 94k, this equates to roughly a 30MB property size for a 32 TB
> system. This file size is not neccessarily huge, but the need to update
> this property every time we DLPAR add or remove an LMB could be
> problematic.
> Every time the property is updated a new copy of the property is made
> with the previous copy being added to the old_properties list. Due to
> the lack of reference counting on properties old versions of a property
> are never free'ed. One a large 32TB system we could easilty do
> several thousands of memory add/remove operations and thus create
> several thousand of copies of this property. This seems a bit wasteful
> with respect to system resources.
> Patch 1/3:
> This patch changes the pseries hotplug memory code to maintain a static
> reference to this property instead of creating a new copy for every LMB
> that we add or remove. In doing this we have to ensure that the property
> remains in BE format so a set of accessor methods are provided to
> get/set values from the property in the proper cpu format.

I missed this when you sent it, and now it doesn't apply anymore. Can
you do a rebase and resend it ?


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