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Fix free memory calculation on v3.14+

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Provide infrastructure to auto-configure to enum and API changes in the
global page stats used for our free memory calculations.

arc_free_memory has been broken since an API change in Linux v3.14:

2016-07-28 v4.8 599d0c95 mm, vmscan: move LRU lists to node
2016-07-28 v4.8 75ef7184 mm, vmstat: add infrastructure for per-node
  vmstats

These commits moved some of global_page_state() into
global_node_page_state(). The API change was particularly egregious as,
instead of breaking the old code, it silently did the wrong thing and we
continued using global_page_state() where we should have been using
global_node_page_state(), thus indexing into the wrong array via
NR_SLAB_RECLAIMABLE et al.

There have been further API changes along the way:

2017-07-06 v4.13 385386cf mm: vmstat: move slab statistics from zone to
  node counters
2017-09-06 v4.14 c41f012a mm: rename global_page_state to
  global_zone_page_state

...and various (incomplete, as it turns out) attempts to accomodate
these changes in ZoL:

2017-08-24 2209e409 Linux 4.8+ compatibility fix for vm stats
2017-09-16 787acae0 Linux 3.14 compat: IO acct, global_page_state, etc
2017-09-19 661907e6 Linux 4.14 compat: IO acct, global_page_state, etc

The config infrastructure provided here resolves these issues going back
to the original API change in v3.14 and is robust against further Linux
changes in this area.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Closes #7170
This commit is contained in:
chrisrd
2018-02-24 03:50:06 +11:00
committed by Brian Behlendorf
parent 7088545d01
commit e9a7729008
8 changed files with 255 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/arc.c
+6 -17
View File
@@ -297,6 +297,7 @@
#include <sys/fs/swapnode.h>
#include <sys/zpl.h>
#include <linux/mm_compat.h>
#include <linux/page_compat.h>
#endif
#include <sys/callb.h>
#include <sys/kstat.h>
@@ -4699,17 +4700,11 @@ arc_free_memory(void)
si_meminfo(&si);
return (ptob(si.freeram - si.freehigh));
#else
#ifdef ZFS_GLOBAL_NODE_PAGE_STATE
return (ptob(nr_free_pages() +
global_node_page_state(NR_INACTIVE_FILE) +
global_node_page_state(NR_INACTIVE_ANON) +
global_node_page_state(NR_SLAB_RECLAIMABLE)));
#else
return (ptob(nr_free_pages() +
global_page_state(NR_INACTIVE_FILE) +
global_page_state(NR_INACTIVE_ANON) +
global_page_state(NR_SLAB_RECLAIMABLE)));
#endif /* ZFS_GLOBAL_NODE_PAGE_STATE */
nr_inactive_file_pages() +
nr_inactive_anon_pages() +
nr_slab_reclaimable_pages()));
#endif /* CONFIG_HIGHMEM */
#else
return (spa_get_random(arc_all_memory() * 20 / 100));
@@ -5121,13 +5116,7 @@ arc_evictable_memory(void)
* Scale reported evictable memory in proportion to page cache, cap
* at specified min/max.
*/
#ifdef ZFS_GLOBAL_NODE_PAGE_STATE
uint64_t min = (ptob(global_node_page_state(NR_FILE_PAGES)) / 100) *
zfs_arc_pc_percent;
#else
uint64_t min = (ptob(global_page_state(NR_FILE_PAGES)) / 100) *
zfs_arc_pc_percent;
#endif
uint64_t min = (ptob(nr_file_pages()) / 100) * zfs_arc_pc_percent;
min = MAX(arc_c_min, MIN(arc_c_max, min));
if (arc_dirty >= min)