Re: [PATCH 2.6.17-rc1-mm1 9/9] AutoPage Migration - V0.2 - hook automigration to migrate-on-fault

Lee Schermerhorn
2006-04-07T20:43:48Z

AutoPage Migration - V0.2 - 9/9 hook automigration to migrate-on-fault

Add a /sys/kernel/migration control--auto_migrate_lazy--to use
migrate-on-fault for auto-migration.

Modify migrate_to_node() to just unmap the eligible pages
via migrate_pages_unmap_only() when MPOL_MF_LAZY flag is set.

This patch depends on the "migrate-on-fault" patch series that
defines the MPOL_MF_LAZY flag and the migrate_pages_unmap_only()
function.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

Index: linux-2.6.16-mm1/mm/mempolicy.c
===================================================================
--- linux-2.6.16-mm1.orig/mm/mempolicy.c 2006-03-23 16:50:30.000000000 -0500
+++ linux-2.6.16-mm1/mm/mempolicy.c 2006-03-23 16:50:36.000000000 -0500
@@ -635,7 +635,11 @@ int migrate_to_node(struct mm_struct *mm
flags | MPOL_MF_DISCONTIG_OK, &pagelist);

if (!list_empty(&pagelist)) {
- err = migrate_pages_to(&pagelist, NULL, dest);
+ if (flags & MPOL_MF_LAZY)
+ err = migrate_pages_unmap_only(&pagelist);
+ else
+ err = migrate_pages_to(&pagelist, NULL, dest);
+
if (!list_empty(&pagelist))
putback_lru_pages(&pagelist);
}
@@ -744,6 +748,9 @@ void auto_migrate_task_memory(void)
*/
BUG_ON(!mm);

+ if (auto_migrate_lazy)
+ flags |= MPOL_MF_LAZY;
+
/*
* Pass destination node as source node plus 'INVERT flag:
* Migrate all pages NOT on destination node.
@@ -1000,7 +1007,6 @@ out:
return err;
}

-
/* Retrieve NUMA policy */
asmlinkage long sys_get_mempolicy(int __user *policy,
unsigned long __user *nmask,
Index: linux-2.6.16-mm1/mm/migrate.c
===================================================================
--- linux-2.6.16-mm1.orig/mm/migrate.c 2006-03-23 16:50:30.000000000 -0500
+++ linux-2.6.16-mm1/mm/migrate.c 2006-03-23 16:50:36.000000000 -0500
@@ -129,6 +129,37 @@ static ssize_t migrate_max_mapcount_stor
}
MIGRATION_ATTR_RW(migrate_max_mapcount);

+/*
+ * auto_migrate_lazy: use "lazy migration"--i.e., migration-on-fault--
+ * for scheduler driven task memory migration.
+ */
+int auto_migrate_lazy = 0;
+
+static int __init set_auto_migrate_lazy(char *str)
+{
+ get_option(&str, &auto_migrate_lazy);
+ return 1;
+}
+
+__setup("auto_migrate_lazy", set_auto_migrate_lazy);
+
+static ssize_t auto_migrate_lazy_show(struct subsystem *subsys, char *page)
+{
+ return sprintf(page, "auto_migrate_lazy %s\n",
+ auto_migrate_lazy ? "on" : "off");
+}
+static ssize_t auto_migrate_lazy_store(struct subsystem *subsys,
+ const char *page, size_t count)
+{
+ unsigned long n = simple_strtoul(page, NULL, 10);
+ if (n)
+ auto_migrate_lazy = 1;
+ else
+ auto_migrate_lazy = 0;
+ return count;
+}
+MIGRATION_ATTR_RW(auto_migrate_lazy);
+
decl_subsys(migration, NULL, NULL);
EXPORT_SYMBOL(migration_subsys);

@@ -136,6 +167,7 @@ static struct attribute *migration_attrs
&auto_migrate_enable_attr.attr,
&auto_migrate_interval_attr.attr,
&migrate_max_mapcount_attr.attr,
+ &auto_migrate_lazy_attr.attr,
NULL
};

Index: linux-2.6.16-mm1/include/linux/auto-migrate.h
===================================================================
--- linux-2.6.16-mm1.orig/include/linux/auto-migrate.h 2006-03-23 16:50:30.000000000 -0500
+++ linux-2.6.16-mm1/include/linux/auto-migrate.h 2006-03-23 16:50:36.000000000 -0500
@@ -21,6 +21,7 @@ extern unsigned long auto_migrate_interv
#define AUTO_MIGRATE_INTERVAL_MAX (300*HZ)

extern unsigned int migrate_max_mapcount;
+extern int auto_migrate_lazy;

#ifdef _LINUX_SCHED_H /* only used where this is defined */
static inline void check_internode_migration(task_t *task, int dest_cpu)
@@ -101,6 +102,7 @@ out:

#define check_migrate_pending() /* NOTHING */
#define migrate_max_mapcount (1)
+#define auto_migrate_lazy (0)

#endif /* CONFIG_MIGRATION */