Hi David,
On 02/15/2013 08:26 AM, David Rientjes wrote:
On Thu, 14 Feb 2013, Jiang Liu wrote:
Hmm, ok. The question is which one is right: the per-node MemTotal is the
amount of present RAM, the spanned range minus holes, and the system
MemTotal is the amount of pages released to the buddy allocator by
bootmem and discounts not only the memory holes but also reserved pages.
Should they both be the amount of RAM present or the amount of unreserved
RAM present?
Hi David,
We have worked out a patch set to address this issue. The first two
patches have been merged into v3.8, and another two patches are queued in
Andrew's mm tree for v3.9.
The patch set introduces a new field named managed_pages into struct
zone to distinguish between pages present in a zone and pages managed by the
buddy system. So
zone->present_pages = zone->spanned_pages - pages_in_hole;
zone->managed_pages = pages_managed_by_buddy_system_in_the_zone;
We have also added a field named "managed" into /proc/zoneinfo, but
haven't touch /proc/meminfo and /sys/devices/system/node/nodex/meminfo yet.
If preferred, we could work out another patch to enhance these two files
as suggested above.
I'm glad this is a known issue that you're working on, but my question
still stands: if MemTotal is going to be consistent throughout
/proc/meminfo and /sys/devices/system/node/nodeX/meminfo, which is
correct? The present RAM minus holes or the amount available to the buddy
allocator not including reserved memory?
What I confuse is why have /proc/meminfo and /proc/vmstat at the same
time, they both use to monitor memory subsystem states. What's the root
reason?
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