On 08/24/2017 05:33 AM, Michael Ellerman wrote:
> John Allen <jal...@linux.vnet.ibm.com> writes:
>
>> Check if an LMB is assigned before attempting to call dlpar_acquire_drc in
>> order to avoid any unnecessary rtas calls. This substantially reduces the
>> running time of memory hot add on lpars with large amounts of memory.
>>
>> Signed-off-by: John Allen <jal...@linux.vnet.ibm.com>
>
> I'll add:
>
> Fixes: c21f515c7436 ("powerpc/pseries: Make the acquire/release of the drc
> for memory a seperate step")
>
> ?
Yes, thanks.
>
> How bad is the slow down, do we need to backport to stable/distros?
On an lpar with 16 TB of memory assigned, I observed that adding 1 GB of
memory took several minutes without this fix and improved to several
seconds with this fix. Yep, this will need to be backported. Memory hotplug
performance is a hot issue for our team right now and we'll want to have
solid performance improvement to give to customers relatively soon.
>
> cheers
>
>
