Re: NUMA policy issues with ZONE_MOVABLE

KAMEZAWA Hiroyuki
2007-07-28T07:28:44Z

On Fri, 27 Jul 2007 16:45:19 +0100
mel@skynet.ie (Mel Gorman) wrote:

> Obvious things that are outstanding;
>
> o Compile-test parisc
> o Split patch in two to keep the zone_idx changes separetly
> o Verify zlccache is not broken
> o Have a version of __alloc_pages take a nodemask and ditch
> bind_zonelist()
>
> I can work on bringing this up to scratch during the cycle.
>
> Patch as follows. Comments?
>

I like this idea in general. My concern is zonelist scan cost.
Hmm, can this be help ?

---
include/linux/mmzone.h | 1
mm/page_alloc.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 50 insertions(+), 2 deletions(-)

Index: linux-2.6.23-rc1.test/include/linux/mmzone.h
===================================================================
--- linux-2.6.23-rc1.test.orig/include/linux/mmzone.h
+++ linux-2.6.23-rc1.test/include/linux/mmzone.h
@@ -406,6 +406,7 @@ struct zonelist_cache;

struct zonelist {
struct zonelist_cache *zlcache_ptr; // NULL or &zlcache
+ unsigned short gfp_skip[MAX_NR_ZONES];
struct zone *zones[MAX_ZONES_PER_ZONELIST + 1]; // NULL delimited
#ifdef CONFIG_NUMA
struct zonelist_cache zlcache; // optional ...
Index: linux-2.6.23-rc1.test/mm/page_alloc.c
===================================================================
--- linux-2.6.23-rc1.test.orig/mm/page_alloc.c
+++ linux-2.6.23-rc1.test/mm/page_alloc.c
@@ -1158,13 +1158,14 @@ get_page_from_freelist(gfp_t gfp_mask, u
int zlc_active = 0; /* set if using zonelist_cache */
int did_zlc_setup = 0; /* just call zlc_setup() one time */
enum zone_type highest_zoneidx = gfp_zone(gfp_mask);
+ int default_skip = zonelist->gfp_skip[highest_zoneidx];

zonelist_scan:
/*
* Scan zonelist, looking for a zone with enough free.
* See also cpuset_zone_allowed() comment in kernel/cpuset.c.
*/
- z = zonelist->zones;
+ z = zonelist->zones + default_skip;

do {
if (should_filter_zone(*z, highest_zoneidx))
@@ -1235,6 +1236,7 @@ __alloc_pages(gfp_t gfp_mask, unsigned i
int do_retry;
int alloc_flags;
int did_some_progress;
+ int gfp_skip = zonelist->gfp_skip[gfp_zone(gfp_mask)];

might_sleep_if(wait);

@@ -1265,7 +1267,7 @@ restart:
if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
goto nopage;

- for (z = zonelist->zones; *z; z++)
+ for (z = zonelist->zones + gfp_skip; *z; z++)
wakeup_kswapd(*z, order);

/*
@@ -2050,6 +2052,50 @@ static void build_zonelist_cache(pg_data

#endif /* CONFIG_NUMA */

+static inline
+unsigned short find_first_zone(enum zone_type target, struct zonelist *zl)
+{
+ unsigned short index = 0;
+ struct zone *z;
+ z = zl->zones[index];
+ while (z != NULL) {
+ if (!should_filter_zone(z, target))
+ return index;
+ z = zl->zones[++index];
+ }
+ return 0;
+}
+/*
+ * record the first available zone per gfp.
+ */
+
+static void build_zonelist_skip(pg_data_t *pgdat)
+{
+ enum zone_type target;
+ unsigned short index;
+ struct zonelist *zl = &pgdat->node_zonelist;
+
+ target = gfp_zone(GFP_KERNEL|GFP_DMA);
+ index = find_first_zone(target, zl);
+ zl->gfp_skip[target] = index;
+
+ target = gfp_zone(GFP_KERNEL|GFP_DMA32);
+ index = find_first_zone(target, zl);
+ zl->gfp_skip[target] = index;
+
+ target = gfp_zone(GFP_KERNEL);
+ index = find_first_zone(target, zl);
+ zl->gfp_skip[target] = index;
+
+ target = gfp_zone(GFP_HIGHUSER);
+ index = find_first_zone(target, zl);
+ zl->gfp_skip[target] = index;
+
+ target = gfp_zone(GFP_HIGHUSER_MOVABLE);
+ index = find_first_zone(target, zl);
+ zl->gfp_skip[target] = index;
+}
+
/* return values int ....just for stop_machine_run() */
static int __build_all_zonelists(void *dummy)
{
@@ -2058,6 +2104,7 @@ static int __build_all_zonelists(void *d
for_each_online_node(nid) {
build_zonelists(NODE_DATA(nid));
build_zonelist_cache(NODE_DATA(nid));
+ build_zonelist_skip(NODE_DATA(nid));
}
return 0;
}