On Mon, May 7, 2012 at 10:33 PM, KOSAKI Motohiro
[off-list ref] wrote:

quoted

quoted

@@ -1204,8 +1265,14 @@ static int __init setup_vmstat(void)

       register_cpu_notifier(&vmstat_notifier);

+       INIT_DELAYED_WORK_DEFERRABLE(&vmstat_monitor_work,
+                               vmstat_update_monitor);
+       queue_delayed_work(system_unbound_wq,
+                               &vmstat_monitor_work,
+                               round_jiffies_relative(HZ));
+
       for_each_online_cpu(cpu)
-               start_cpu_timer(cpu);
+               setup_cpu_timer(cpu);
 #endif
 #ifdef CONFIG_PROC_FS
       proc_create("buddyinfo", S_IRUGO,
NULL,&fragmentation_file_operations);

So the monitoring thread just bounces around the system? Hope that the
scheduler does the right thing to keep it on processors that do some other
work.

Good point. Usually, all cpus have update items and monitor worker only
makes
new noise. I think this feature is only useful some hpc case.  So I wonder
if
this vmstat improvemnt can integrate Frederic's Nohz cpusets activity. I.e.
vmstat-update integrate timer house keeping and automatically stop when
stopping
hz house keeping.

I wrote this and the previous IPI patch set explicitly to use with
Frederic's  Nohz stuff
for CPU isolation. It just seemed at the time to be wrong to tie them
together - I mean
people that do CPU isolation can enjoy this even if they don't want to
kill the tick (that
comes with its own overhead for doing system calls, for example).

Thanks!
Gilad


-- 
Gilad Ben-Yossef
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gilad@benyossef.com
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situation where the homework eats your dog?"
 -- Jean-Baptiste Queru

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