From: Martin Hicks <mort@sgi.com>
This is the core of the (much simplified) early reclaim. The goal of this
patch is to reclaim some easily-freed pages from a zone before falling back
onto another zone.
One of the major uses of this is NUMA machines. With the default allocator
behavior the allocator would look for memory in another zone, which might be
off-node, before trying to reclaim from the current zone.
This adds a zone tuneable to enable early zone reclaim. It is selected on a
per-zone basis and is turned on/off via syscall.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
arch/i386/kernel/syscall_table.S | 2 -
arch/ia64/kernel/entry.S | 2 -
include/asm-i386/unistd.h | 2 -
include/asm-ia64/unistd.h | 1
include/linux/mmzone.h | 6 +++
include/linux/swap.h | 1
kernel/sys_ni.c | 1
mm/page_alloc.c | 31 ++++++++++++++++--
mm/vmscan.c | 64 +++++++++++++++++++++++++++++++++++++++
9 files changed, 103 insertions(+), 7 deletions(-)
diff -puN arch/i386/kernel/syscall_table.S~vm-early-zone-reclaim arch/i386/kernel/syscall_table.S
--- 25/arch/i386/kernel/syscall_table.S~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/arch/i386/kernel/syscall_table.S 2005-06-05 22:07:11.000000000 -0700
@@ -251,7 +251,7 @@ ENTRY(sys_call_table)
.long sys_io_submit
.long sys_io_cancel
.long sys_fadvise64 /* 250 */
- .long sys_ni_syscall
+ .long sys_set_zone_reclaim
.long sys_exit_group
.long sys_lookup_dcookie
.long sys_epoll_create
diff -puN arch/ia64/kernel/entry.S~vm-early-zone-reclaim arch/ia64/kernel/entry.S
--- 25/arch/ia64/kernel/entry.S~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/arch/ia64/kernel/entry.S 2005-06-05 22:07:11.000000000 -0700
@@ -1573,7 +1573,7 @@ sys_call_table:
data8 sys_keyctl
data8 sys_ni_syscall
data8 sys_ni_syscall // 1275
- data8 sys_ni_syscall
+ data8 sys_set_zone_reclaim
data8 sys_ni_syscall
data8 sys_ni_syscall
data8 sys_ni_syscall
diff -puN include/asm-i386/unistd.h~vm-early-zone-reclaim include/asm-i386/unistd.h
--- 25/include/asm-i386/unistd.h~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/include/asm-i386/unistd.h 2005-06-05 22:07:11.000000000 -0700
@@ -256,7 +256,7 @@
#define __NR_io_submit 248
#define __NR_io_cancel 249
#define __NR_fadvise64 250
-
+#define __NR_set_zone_reclaim 251
#define __NR_exit_group 252
#define __NR_lookup_dcookie 253
#define __NR_epoll_create 254
diff -puN include/asm-ia64/unistd.h~vm-early-zone-reclaim include/asm-ia64/unistd.h
--- 25/include/asm-ia64/unistd.h~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/include/asm-ia64/unistd.h 2005-06-05 22:07:11.000000000 -0700
@@ -263,6 +263,7 @@
#define __NR_add_key 1271
#define __NR_request_key 1272
#define __NR_keyctl 1273
+#define __NR_set_zone_reclaim 1276
#ifdef __KERNEL__
diff -puN include/linux/mmzone.h~vm-early-zone-reclaim include/linux/mmzone.h
--- 25/include/linux/mmzone.h~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/include/linux/mmzone.h 2005-06-05 22:07:11.000000000 -0700
@@ -145,6 +145,12 @@ struct zone {
int all_unreclaimable; /* All pages pinned */
/*
+ * Does the allocator try to reclaim pages from the zone as soon
+ * as it fails a watermark_ok() in __alloc_pages?
+ */
+ int reclaim_pages;
+
+ /*
* prev_priority holds the scanning priority for this zone. It is
* defined as the scanning priority at which we achieved our reclaim
* target at the previous try_to_free_pages() or balance_pgdat()
diff -puN include/linux/swap.h~vm-early-zone-reclaim include/linux/swap.h
--- 25/include/linux/swap.h~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/include/linux/swap.h 2005-06-05 22:07:11.000000000 -0700
@@ -173,6 +173,7 @@ extern void swap_setup(void);
/* linux/mm/vmscan.c */
extern int try_to_free_pages(struct zone **, unsigned int, unsigned int);
+extern int zone_reclaim(struct zone *, unsigned int, unsigned int);
extern int shrink_all_memory(int);
extern int vm_swappiness;
diff -puN kernel/sys_ni.c~vm-early-zone-reclaim kernel/sys_ni.c
--- 25/kernel/sys_ni.c~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/kernel/sys_ni.c 2005-06-05 22:07:11.000000000 -0700
@@ -77,6 +77,7 @@ cond_syscall(sys_request_key);
cond_syscall(sys_keyctl);
cond_syscall(compat_sys_keyctl);
cond_syscall(compat_sys_socketcall);
+cond_syscall(sys_set_zone_reclaim);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
diff -puN mm/page_alloc.c~vm-early-zone-reclaim mm/page_alloc.c
--- 25/mm/page_alloc.c~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/mm/page_alloc.c 2005-06-05 22:07:11.000000000 -0700
@@ -724,6 +724,14 @@ int zone_watermark_ok(struct zone *z, in
return 1;
}
+static inline int
+check_zone_reclaim(struct zone *z, unsigned int gfp_mask)
+{
+ if (!z->reclaim_pages)
+ return 0;
+ return 1;
+}
+
/*
* This is the 'heart' of the zoned buddy allocator.
*/
@@ -763,14 +771,29 @@ __alloc_pages(unsigned int __nocast gfp_
restart:
/* Go through the zonelist once, looking for a zone with enough free */
for (i = 0; (z = zones[i]) != NULL; i++) {
-
- if (!zone_watermark_ok(z, order, z->pages_low,
- classzone_idx, 0, 0))
- continue;
+ int do_reclaim = check_zone_reclaim(z, gfp_mask);
if (!cpuset_zone_allowed(z))
continue;
+ /*
+ * If the zone is to attempt early page reclaim then this loop
+ * will try to reclaim pages and check the watermark a second
+ * time before giving up and falling back to the next zone.
+ */
+ zone_reclaim_retry:
+ if (!zone_watermark_ok(z, order, z->pages_low,
+ classzone_idx, 0, 0)) {
+ if (!do_reclaim)
+ continue;
+ else {
+ zone_reclaim(z, gfp_mask, order);
+ /* Only try reclaim once */
+ do_reclaim = 0;
+ goto zone_reclaim_retry;
+ }
+ }
+
page = buffered_rmqueue(z, order, gfp_mask);
if (page)
goto got_pg;
diff -puN mm/vmscan.c~vm-early-zone-reclaim mm/vmscan.c
--- 25/mm/vmscan.c~vm-early-zone-reclaim 2005-06-05 22:07:11.000000000 -0700
+++ 25-akpm/mm/vmscan.c 2005-06-05 22:07:11.000000000 -0700
@@ -1326,3 +1326,67 @@ static int __init kswapd_init(void)
}
module_init(kswapd_init)
+
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order)
+{
+ struct scan_control sc;
+ int nr_pages = 1 << order;
+ int total_reclaimed = 0;
+
+ /* The reclaim may sleep, so don't do it if sleep isn't allowed */
+ if (!(gfp_mask & __GFP_WAIT))
+ return 0;
+ if (zone->all_unreclaimable)
+ return 0;
+
+ sc.gfp_mask = gfp_mask;
+ sc.may_writepage = 0;
+ sc.may_swap = 0;
+ sc.nr_mapped = read_page_state(nr_mapped);
+ sc.nr_scanned = 0;
+ sc.nr_reclaimed = 0;
+ /* scan at the highest priority */
+ sc.priority = 0;
+
+ if (nr_pages > SWAP_CLUSTER_MAX)
+ sc.swap_cluster_max = nr_pages;
+ else
+ sc.swap_cluster_max = SWAP_CLUSTER_MAX;
+
+ shrink_zone(zone, &sc);
+ total_reclaimed = sc.nr_reclaimed;
+
+ return total_reclaimed;
+}
+
+asmlinkage long sys_set_zone_reclaim(unsigned int node, unsigned int zone,
+ unsigned int state)
+{
+ struct zone *z;
+ int i;
+
+ if (node >= MAX_NUMNODES || !node_online(node))
+ return -EINVAL;
+
+ /* This will break if we ever add more zones */
+ if (!(zone & (1<<ZONE_DMA|1<<ZONE_NORMAL|1<<ZONE_HIGHMEM)))
+ return -EINVAL;
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ if (!(zone & 1<<i))
+ continue;
+
+ z = &NODE_DATA(node)->node_zones[i];
+
+ if (state)
+ z->reclaim_pages = 1;
+ else
+ z->reclaim_pages = 0;
+ }
+
+ return 0;
+}
_