On 25.09.19 09:37, David Hildenbrand wrote: > On 10.09.19 18:39, David Hildenbrand wrote: >> We can simply store the pages in a list (page->lru), no need for a >> separate data structure (+ complicated handling). This is how most >> other balloon drivers store allocated pages without additional tracking >> data. >> >> For the notifiers, use page_to_pfn() to check if a page is in the >> applicable range. plpar_page_set_loaned()/plpar_page_set_active() were >> called with __pa(page_address()) for now, I assume we can simply switch >> to page_to_phys() here. The pfn_to_kaddr() handling is now mostly gone. >> >> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> >> Cc: Paul Mackerras <pau...@samba.org> >> Cc: Michael Ellerman <m...@ellerman.id.au> >> Cc: Arun KS <aru...@codeaurora.org> >> Cc: Pavel Tatashin <pasha.tatas...@soleen.com> >> Cc: Thomas Gleixner <t...@linutronix.de> >> Cc: Andrew Morton <a...@linux-foundation.org> >> Cc: Vlastimil Babka <vba...@suse.cz> >> Signed-off-by: David Hildenbrand <da...@redhat.com> >> --- >> >> Only compile-tested. I hope the page_to_phys() thingy is correct and I >> didn't mess up something else / ignoring something important why the array >> is needed. >> >> I stumbled over this while looking at how the memory isolation notifier is >> used - and wondered why the additional array is necessary. Also, I think >> by switching to the generic balloon compaction mechanism, we could get >> rid of the memory hotplug notifier and the memory isolation notifier in >> this code, as the migration capability of the inflated pages is the real >> requirement: >> commit 14b8a76b9d53346f2871bf419da2aaf219940c50 >> Author: Robert Jennings <r...@linux.vnet.ibm.com> >> Date: Thu Dec 17 14:44:52 2009 +0000 >> >> powerpc: Make the CMM memory hotplug aware >> >> The Collaborative Memory Manager (CMM) module allocates individual >> pages >> over time that are not migratable. On a long running system this >> can >> severely impact the ability to find enough pages to support a >> hotplug >> memory remove operation. >> [...] >> >> Thoughts? > > Ping, is still feature still used at all? > > If nobody can test, any advise on which HW I need and how to trigger it? >
So ... if CMM is no longer alive I propose ripping it out completely. Does anybody know if this feature is still getting used? Getting rid of the memory isolation notifier sounds desirable - either by scrapping CMM or by properly wiring up balloon compaction. -- Thanks, David / dhildenb
