Hi!
I was trying to write a multigraph munin plugin to graph /proc/zoneinfo,
somewhere between the buddyinfo and memory plugins, to help get to the
bottom of the huge order-0 fragmentation that seems to be only happening
in the DMA32 zone on our servers (since at least 2.6.26). I figured it
would make a nice stacked graph similar to the memory graph, where
everything could add up to the size of the zone (or total to the whole
system memory), but I'm having trouble finding out which page states can
overlap.
It seems that nr_inactive_anon and nr_active_anon never seem to add to
nr_anon_pages, and same with nr_inactive_file and nr_active_file to
nr_file_pages. In the below random case from my desktop, it seems there
are more active and inactive anon pages than the actual nr_anon_pages,
so the error is happening both ways here.
I tried to dig through the kernel to find the paths that relate to how
file pages are allocated, but it seems like the LRU parts are separate
and a little confusing to follow. Is there anything useful I could
follow here, or should I just give up and make it a regular line graph?
This graph is just the stacked output of /proc/zoneinfo for DMA32 on a
random server (in pages for now, not bytes). It _almost_ looks like it
would add up to the same number if I just dropped nr_anon_pages and
nr_file_pages and made nr_dirty and nr_writeback lines instead of stacks,
but _not quite_. (I excluded nr_vmscan_write, nr_dirtied, nr_written as
they seem to be counters.)
Simon-
Example from my desktop that doesn't add up for file or anon pages:
Node 0, zone DMA32
pages free 26961
min 1426
low 1782
high 2139
scanned 0
spanned 520128
present 513016
nr_free_pages 26961
nr_inactive_anon 8185
nr_active_anon 130189
nr_inactive_file 149021
nr_active_file 153911
nr_unevictable 1
nr_mlock 1
nr_anon_pages 137756
nr_mapped 17376
nr_file_pages 303551
nr_dirty 51
nr_writeback 0
nr_slab_reclaimable 26394
nr_slab_unreclaimable 4719
nr_page_table_pages 2316
nr_kernel_stack 248
nr_unstable 0
nr_bounce 0
nr_vmscan_write 346710
nr_writeback_temp 0
nr_isolated_anon 0
nr_isolated_file 0
nr_shmem 619
nr_dirtied 25820454
nr_written 17165935
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