(1/3/12 2:00 PM), Gilad Ben-Yossef wrote:
2012/1/3 KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxx>:
(1/2/12 5:24 AM), Gilad Ben-Yossef wrote:
This patch introduces two new vmstat counters: pcp_global_drain
that counts the number of times a per-cpu pages global drain was
requested and pcp_global_ipi_saved that counts the number of times
the number of CPUs with per-cpu pages in any zone were less then
1/2 of the number of online CPUs.
The patch purpose is to show the usefulness of only sending an IPI
asking to drain per-cpu pages to CPUs that actually have them
instead of a blind global IPI. It is probably not useful by itself.
...
}
on_each_cpu_mask(cpus_with_pcps, drain_local_pages, NULL, 1);
+
+ count_vm_event(PCP_GLOBAL_DRAIN);
+ if (cpumask_weight(cpus_with_pcps)< (cpumask_weight(cpu_online_mask) / 2))
+ count_vm_event(PCP_GLOBAL_IPI_SAVED);
NAK.
PCP_GLOBAL_IPI_SAVED is only useful at development phase. I can't
imagine normal admins use it.
As the description explains, the purpose of the patch is to show why i
claim the previous
patch is useful. I did not meant it to be applied to mainline. My
apologies for not
stating this more clearly. I agree it is not useful for an admin,
although perhaps PCP_GLOBAL_DRAIN
alone might - I am not sure?
Until we found a good usecase, we shouldn't append any stat. It is not
zero overhead even though nobody uses.
That's why I almost always disagree adding statistics from point of
developers view.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>