Re: [PATCH v3 1/2] memory-hotplug: introduce CONFIG_HAVE_BOOTMEM_INFO_NODE and revert register_page_bootmem_info_node() when platform not support
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- To: Lin Feng <linfeng@xxxxxxxxxxxxxx>
- Subject: Re: [PATCH v3 1/2] memory-hotplug: introduce CONFIG_HAVE_BOOTMEM_INFO_NODE and revert register_page_bootmem_info_node() when platform not support
- From: Michal Hocko <mhocko@xxxxxxx>
- Date: Thu, 17 Jan 2013 14:05:09 +0100
- Cc: akpm@xxxxxxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, tglx@xxxxxxxxxxxxx, mingo@xxxxxxxxxx, hpa@xxxxxxxxx, jbeulich@xxxxxxxx, dhowells@xxxxxxxxxx, wency@xxxxxxxxxxxxxx, isimatu.yasuaki@xxxxxxxxxxxxxx, paul.gortmaker@xxxxxxxxxxxxx, laijs@xxxxxxxxxxxxxx, kamezawa.hiroyu@xxxxxxxxxxxxxx, mel@xxxxxxxxx, minchan@xxxxxxxxxx, aquini@xxxxxxxxxx, jiang.liu@xxxxxxxxxx, tony.luck@xxxxxxxxx, fenghua.yu@xxxxxxxxx, benh@xxxxxxxxxxxxxxxxxxx, paulus@xxxxxxxxx, schwidefsky@xxxxxxxxxx, heiko.carstens@xxxxxxxxxx, davem@xxxxxxxxxxxxx, michael@xxxxxxxxxxxxxx, gerald.schaefer@xxxxxxxxxx, gregkh@xxxxxxxxxxxxxxxxxxx, x86@xxxxxxxxxx, linux390@xxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, sparclinux@xxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, tangchen@xxxxxxxxxxxxxx
- In-reply-to: <50F7D456.9000904@cn.fujitsu.com>
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- References: <1358324059-9608-1-git-send-email-linfeng@cn.fujitsu.com> <1358324059-9608-2-git-send-email-linfeng@cn.fujitsu.com> <20130116141436.GE343@dhcp22.suse.cz> <50F7D456.9000904@cn.fujitsu.com>
- User-agent: Mutt/1.5.21 (2010-09-15)
On Thu 17-01-13 18:37:10, Lin Feng wrote:
[...]
> > I am still not sure I understand the relation to MEMORY_HOTREMOVE.
> > Is register_page_bootmem_info_node required/helpful even if
> > !CONFIG_MEMORY_HOTREMOVE?
> From old kenrel's view register_page_bootmem_info_node() is defined in
> CONFIG_MEMORY_HOTPLUG_SPARSE, it registers some info for
> memory hotplug/remove. If we don't use MEMORY_HOTPLUG feature, this
> function is empty, we don't need the info at all.
> So this info is not required/helpful if !CONFIG_MEMORY_HOTREMOVE.
OK, then I suggest moving it under CONFIG_MEMORY_HOTREMOVE guards rather
than CONFIG_MEMORY_HOTPLUG.
> > Also, now that I am thinking about that more, maybe it would
> > be cleaner to put the select into arch/x86/Kconfig and do it
> > same as ARCH_ENABLE_MEMORY_{HOTPLUG,HOTREMOVE} (and name it
> > ARCH_HAVE_BOOTMEM_INFO_NODE).
> >
> Maybe put it in mm/Kconfig is a better choice, because if one day
> someone implements the register_page_bootmem_info_node() for other
> archs they will get some clues here, that's it has been implemented on
> x86_64.
> But I'm not so sure...
My understanding is that doing that in arch code is more appropriate
because it makes the generic code less complicated. But I do not have
any strong opinion on that. Looking at other ARCH_ENABLE_MEMORY_HOTPLUG
and others suggests that we should be consistent with that.
Thanks!
--
Michal Hocko
SUSE Labs
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