Migration Cache 5/N - use migration cache for lazy migration
Add migration cache vm statistics. We might want some statistics
for the migration cache, should it be merged. Here's a start.
Note: the '_NOENT stats are mostly for debugging.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
include/linux/vmstat.h | 5 +++++
mm/swap_state.c | 11 +++++++++--
mm/vmstat.c | 8 ++++++++
3 files changed, 22 insertions(+), 2 deletions(-)
Index: linux-2.6.36-mmotm-101103-1217/include/linux/vmstat.h
===================================================================
--- linux-2.6.36-mmotm-101103-1217.orig/include/linux/vmstat.h
+++ linux-2.6.36-mmotm-101103-1217/include/linux/vmstat.h
@@ -65,6 +65,11 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
AUTOMIG_TASKS_MIGRATED,
AUTOMIG_PGSCANNED, AUTOMIG_PGSELECTED, AUTOMIG_PGFAILED,
#endif
+#ifdef CONFIG_MIGRATION_CACHE
+ MIGCACHE_ADD, MIGCACHE_REMOVE,
+ MIGCACHE_DUP, MIGCACHE_FREE,
+ MIGCACHE_DUP_NOENT, MIGCACHE_FREE_NOENT,
+#endif
NR_VM_EVENT_ITEMS
};
Index: linux-2.6.36-mmotm-101103-1217/mm/swap_state.c
===================================================================
--- linux-2.6.36-mmotm-101103-1217.orig/mm/swap_state.c
+++ linux-2.6.36-mmotm-101103-1217/mm/swap_state.c
@@ -123,10 +123,13 @@ int migration_duplicate(swp_entry_t entr
spin_lock_irq(&migration_space.tree_lock);
cnt = idr_find(&migration_idr, (int)swp_offset(entry));
- if (cnt)
+ if (cnt) {
+ count_vm_event(MIGCACHE_DUP);
atomic_inc(&cnt->i);
- else
+ } else {
+ count_vm_event(MIGCACHE_DUP_NOENT);
err = -ENOENT;
+ }
spin_unlock_irq(&migration_space.tree_lock);
return err;
}
@@ -197,6 +200,7 @@ static void __remove_from_migration_cach
radix_tree_delete(&migration_space.page_tree, id);
idr_remove(&migration_idr, (int)id);
+ count_vm_event(MIGCACHE_REMOVE);
}
/*
@@ -219,12 +223,14 @@ void __migration_remove_reference(struct
cnt = idr_find(&migration_idr, offset);
if (!cnt) {
spin_unlock_irq(&migration_space.tree_lock);
+ count_vm_event(MIGCACHE_FREE_NOENT);
WARN_ONCE(1, "No migration cache 'id' for entry %d\n", offset);
return;
}
VM_BUG_ON(!atomic_read(&cnt->i));
+ count_vm_event(MIGCACHE_FREE);
if (atomic_sub_and_test(1, &cnt->i)) {
__remove_from_migration_cache(page, entry.val);
spin_unlock_irq(&migration_space.tree_lock);
@@ -299,6 +305,7 @@ int add_to_migration_cache(struct page *
set_page_private(page, entry.val);
SetPageSwapCache(page);
SetPageUptodate(page); /* like __add_to_swap() */
+ count_vm_event(MIGCACHE_ADD);
}
spin_unlock_irq(&migration_space.tree_lock);
radix_tree_preload_end();
Index: linux-2.6.36-mmotm-101103-1217/mm/vmstat.c
===================================================================
--- linux-2.6.36-mmotm-101103-1217.orig/mm/vmstat.c
+++ linux-2.6.36-mmotm-101103-1217/mm/vmstat.c
@@ -875,6 +875,14 @@ static const char * const vmstat_text[]
"automig_pgs_selected",
"automig_pgs_failed",
#endif
+#ifdef CONFIG_MIGRATION_CACHE
+ "migration_cache_adds",
+ "migration_cache_removes",
+ "migration_cache_dups",
+ "migration_cache_frees",
+ "migration_cache_dup_noent",
+ "migration_cache_free_noent",
+#endif
#endif
};
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