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authorChristoph Lameter <clameter@sgi.com>2007-05-09 05:35:12 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 15:30:56 -0400
commitd1187ed21026fd512b87851d0ca26d9ae16f9059 (patch)
tree35d77758f134f3b69d3e00ca042a5d5ca6a59373 /include/linux/vmstat.h
parent455c017ae3934797653549704c286e7bcc3a9397 (diff)
vmstat: use our own timer events
vmstat is currently using the cache reaper to periodically bring the statistics up to date. The cache reaper does only exists in SLUB as a way to provide compatibility with SLAB. This patch removes the vmstat calls from the slab allocators and provides its own handling. The advantage is also that we can use a different frequency for the updates. Refreshing vm stats is a pretty fast job so we can run this every second and stagger this by only one tick. This will lead to some overlap in large systems. F.e a system running at 250 HZ with 1024 processors will have 4 vm updates occurring at once. However, the vm stats update only accesses per node information. It is only necessary to stagger the vm statistics updates per processor in each node. Vm counter updates occurring on distant nodes will not cause cacheline contention. We could implement an alternate approach that runs the first processor on each node at the second and then each of the other processor on a node on a subsequent tick. That may be useful to keep a large amount of the second free of timer activity. Maybe the timer folks will have some feedback on this one? [jirislaby@gmail.com: add missing break] Cc: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/vmstat.h')
-rw-r--r--include/linux/vmstat.h3
1 files changed, 0 insertions, 3 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index acb1f105870c..d9325cf8a134 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -212,8 +212,6 @@ extern void dec_zone_state(struct zone *, enum zone_stat_item);
212extern void __dec_zone_state(struct zone *, enum zone_stat_item); 212extern void __dec_zone_state(struct zone *, enum zone_stat_item);
213 213
214void refresh_cpu_vm_stats(int); 214void refresh_cpu_vm_stats(int);
215void refresh_vm_stats(void);
216
217#else /* CONFIG_SMP */ 215#else /* CONFIG_SMP */
218 216
219/* 217/*
@@ -260,7 +258,6 @@ static inline void __dec_zone_page_state(struct page *page,
260#define mod_zone_page_state __mod_zone_page_state 258#define mod_zone_page_state __mod_zone_page_state
261 259
262static inline void refresh_cpu_vm_stats(int cpu) { } 260static inline void refresh_cpu_vm_stats(int cpu) { }
263static inline void refresh_vm_stats(void) { }
264#endif 261#endif
265 262
266#endif /* _LINUX_VMSTAT_H */ 263#endif /* _LINUX_VMSTAT_H */