On 06/27/2016 10:46 PM, Michael Ellerman wrote: > On Mon, 2016-06-27 at 09:41 -0500, Nathan Fontenot wrote: >> On 06/24/2016 12:35 AM, Michael Ellerman wrote: >>> On Mon, 2016-06-20 at 21:14 -0500, Nathan Fontenot wrote: >>>> On 06/20/2016 07:57 PM, Michael Ellerman wrote: >>>>> On Mon, 2016-06-20 at 08:51 -0500, Nathan Fontenot wrote: >>>>> >>>>>> Auto online hotplugged memory >>>>>> >>>>>> A recent update (commit id 31bc3858ea3) to the core mm hotplug code >>>>>> introduced the memhp_auto_online variable to allow for automatically >>>>>> onlining memory that is added. >>>>>> >>>>>> This patch update the pseries memory hotplug code to enable this so that >>>>>> any memory DLPAR added to the system is automatically onlined. The code >>>>>> to add the memory block for memory added from add_memory() is removed as >>>>>> this is not needed, the memory_add code does this. >>>>> >>>>> Is this a bug fix, or just a cleanup? >>>> >>>> Hmmm.. some cleanup and some new feature. The removal of the memblock_add() >>>> call is a cleanup and the setting of the memhp_auto_online variable is >>>> taking advantage of a feature I was not previously aware of. >>> >>> OK. Looking at usage of memhp_auto_online it's not clear to me that you're >>> supposed to be setting it in arch code. >>> >>> eg. if I build my kernel with CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n, I will >>> expect it to not be onlined by default. >>> >>> Similarly if I boot with memhp_default_state=offline on the kernel command >>> line. >>> >>> But this patch would then mean it is onlined by default. So that seems kind >>> of >>> confusing for users. >> >> Yes, but we already online memory when it is DLPAR added to the system. This >> has >> always been the default behavior for pseries. I was using the >> memhp_auto_online >> setting so that the memory will be added as part of the memory_add call >> instead >> of having to online the memory as a separate step in the pseries code. >> >> In other words, I am not changing the existing behavior of pseries code. > > Yep, that's good. > > What's not good is giving the user an option and then ignoring it.
True, I just trying to preserve existing behavior. > >> Perhaps something a bit different? I could save and restore the >> memhp_auto_online >> setting across the call to memory_add, or perhpas ther should be an >> add_memory_and_online() variant of the add_memory() call that always onlines >> memory. > > No I think we should just honor the setting. > > To retain the existing behavour on pseries we just set > CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y > in the pseries defconfig. > > That way users can control the behaviour, which is good, and all the existing > documentation applies equally to powerpc as other arches. If we do something > different, like force onlining it, then we need to go and update all the docs > to > say "memhp_auto_online - ignored on powerpc". > Sounds good, I'll send a new patch to set the config option for pseries and update the dlpar memory add code accordingly. Thanks, -Nathan _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev