Collect info about the global available memory and its consumption speed.
The data are used by the stateful method to estimate the thrashing threshold.
They are the decisive factor of the correctness/accuracy of the resulting
read-ahead size.
The accountings are done on a per-node basis. On NUMA systems, it works for
the two common real-world schemes:
- the reader process allocates caches in a node affined manner;
- the reader process allocates caches _balancely_ from a set of nodes.
Signed-off-by: Wu Fengguang <[email protected]>
DESC
Apply type enum zone_type (readahead)
EDESC
From: Christoph Lameter <[email protected]>
After we have done this we can now do some typing cleanup.
The memory policy layer keeps a policy_zone that specifies
the zone that gets memory policies applied. This variable
can now be of type enum zone_type.
The check_highest_zone function and the build_zonelists funnctionm must
then also take a enum zone_type parameter.
Plus there are a number of loops over zones that also should use
zone_type.
We run into some troubles at some points with functions that need a
zone_type variable to become -1. Fix that up.
Signed-off-by: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
--- linux-2.6.19-rc5-mm2.orig/include/linux/mmzone.h
+++ linux-2.6.19-rc5-mm2/include/linux/mmzone.h
@@ -218,6 +218,7 @@ struct zone {
unsigned long nr_active;
unsigned long nr_inactive;
unsigned long pages_scanned; /* since last reclaim */
+ unsigned long total_scanned; /* accumulated, may overflow */
int all_unreclaimable; /* All pages pinned */
/* A count of how many reclaimers are scanning this zone */
@@ -464,6 +465,8 @@ void __get_zone_counts(unsigned long *ac
unsigned long *free, struct pglist_data *pgdat);
void get_zone_counts(unsigned long *active, unsigned long *inactive,
unsigned long *free);
+unsigned long nr_free_inactive_pages_node(int nid);
+unsigned long nr_scanned_pages_node(int nid);
void build_all_zonelists(void);
void wakeup_kswapd(struct zone *zone, int order);
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
--- linux-2.6.19-rc5-mm2.orig/mm/page_alloc.c
+++ linux-2.6.19-rc5-mm2/mm/page_alloc.c
@@ -1489,6 +1489,37 @@ unsigned int nr_free_pagecache_pages(voi
return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER));
}
+/*
+ * Amount of free+inactive RAM in a node.
+ */
+unsigned long nr_free_inactive_pages_node(int nid)
+{
+ enum zone_type i;
+ unsigned long sum = 0;
+ struct zone *zones = NODE_DATA(nid)->node_zones;
+
+ for (i = 0; i < MAX_NR_ZONES; i++)
+ sum += zones[i].nr_inactive +
+ zones[i].free_pages - zones[i].pages_low;
+
+ return sum;
+}
+
+/*
+ * Accumulated scanned pages in a node.
+ */
+unsigned long nr_scanned_pages_node(int nid)
+{
+ enum zone_type i;
+ unsigned long sum = 0;
+ struct zone *zones = NODE_DATA(nid)->node_zones;
+
+ for (i = 0; i < MAX_NR_ZONES; i++)
+ sum += zones[i].total_scanned;
+
+ return sum;
+}
+
static inline void show_node(struct zone *zone)
{
if (NUMA_BUILD)
--- linux-2.6.19-rc5-mm2.orig/mm/vmscan.c
+++ linux-2.6.19-rc5-mm2/mm/vmscan.c
@@ -683,6 +683,7 @@ static unsigned long shrink_inactive_lis
&page_list, &nr_scan);
zone->nr_inactive -= nr_taken;
zone->pages_scanned += nr_scan;
+ zone->total_scanned += nr_scan;
spin_unlock_irq(&zone->lru_lock);
nr_scanned += nr_scan;
--
On Wed, 15 Nov 2006, Wu Fengguang wrote:
> Collect info about the global available memory and its consumption speed.
> The data are used by the stateful method to estimate the thrashing threshold.
Looks like you should use a ZVC counter for total scanned. See
include/linux/mmzone.h.
On Wed, Nov 15, 2006 at 08:54:44AM -0800, Christoph Lameter wrote:
> On Wed, 15 Nov 2006, Wu Fengguang wrote:
>
> > Collect info about the global available memory and its consumption speed.
> > The data are used by the stateful method to estimate the thrashing threshold.
>
> Looks like you should use a ZVC counter for total scanned. See
> include/linux/mmzone.h.
OK.
By using zone.total_scanned, I have chose an easy way :)
To do the general vm timing in something like zone.vm_stat[NR_SCAN_INACTIVE],
a set of new functions will be required:
global_page_state_raw()
zone_page_state_raw()
node_page_state_raw()
They do not check overflows, so that we can do
time_elapsed = new_raw_value - old_raw_value;
However, before introducing the ugly *_raw() functions, I'd like to know if
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
really helps some big NUMA system. I suspect object counters like
NR_FILE_PAGES will _never_ overflow, and an accumulated counter like
NR_VMSCAN_WRITE is expected to overflow. In either case, it is ok to
return an unsigned long raw counter.
Regards,
Wu