On 02.11.23 17:02, Pasha Tatashin wrote:
On Thu, Nov 2, 2023 at 11:53 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
On 02.11.23 16:50, Pasha Tatashin wrote:
Adding reserved memory to MemTotal is a cleaner approach IMO as well.
But it changes the semantics of MemTotal, which may have compatibility
issues.
I object.
Could you please elaborate what you object (and why): you object that
it will have compatibility issues, or you object to include memblock
reserves into MemTotal?
Sorry, I object to changing the semantics of MemTotal. MemTotal is
traditionally the memory managed by the buddy, not all memory in the
system. I know people/scripts that are relying on that [although it's
been source of confusion a couple of times].
What if one day we change so that struct pages are allocated from
buddy allocator (i.e. allocate deferred struct pages from buddy) will
It does on memory hotplug. But for things like crashkernel size
detection doesn't really care about that.
it break those MemTotal scripts? What if the size of struct pages
changes significantly, but the overhead will come from other metadata
(i.e. memdesc) will that break those scripts? I feel like struct page
Probably; but ideally the metadata overhead will be smaller with
memdesc. And we'll talk about that once it gets real ;)
memory should really be included into MemTotal, otherwise we will have
this struggle in the future when we try to optimize struct page
memory.
How far do we want to go, do we want to include crashkernel reserved
memory in MemTotal because it is system memory? Only metadata? what else
allocated using memblock?
Again, right now it's simple: MemTotal is memory managed by the buddy.
The spirit of this patch set is good, modifying existing counters needs
good justification.
--
Cheers,
David / dhildenb
