On Wed, 13 Apr 2011 17:47:01 -0700 (PDT)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
> On Thu, 14 Apr 2011, KAMEZAWA Hiroyuki wrote:
>
> > > I'm wondering if we can just modify count_vm_event() directly for
> > > CONFIG_CGROUP_MEM_RES_CTLR so that we automatically track all vmstat items
> > > (those in enum vm_event_item) for each memcg. We could add an array of
> > > NR_VM_EVENT_ITEMS into each struct mem_cgroup to be incremented on
> > > count_vm_event() for current's memcg.
> > >
> > > If that's done, we wouldn't have to add additional calls for every vmstat
> > > item we want to duplicate from the global counters.
> > >
> >
> > Maybe we do that finally.
> >
> > For now, IIUC, over 50% of VM_EVENTS are needless for memcg (ex. per zone stats)
> > and this array consumes large size of percpu area. I think we need to select
> > events carefully even if we do that. And current memcg's percpu stat is mixture
> > of vm_events and vm_stat. We may need to sort out them and re-design it.
> > My concern is that I'm not sure we have enough percpu area for vmstat+vmevents
> > for 1000+ memcg, and it's allowed even if we can do.
> >
>
> What I proposed above was adding an array directly into struct mem_cgroup
> so that we don't collect the stats percpu, they are incremented directly
> in the mem_cgroup. Perhaps if we separated enum vm_event_item out into
> two separate arrays (those useful only globally and those useful for both
> global and memcg), then this would be simple.
>
> Something like
>
> enum vm_event_item {
> PGPGIN,
> PGPGOUT,
> PSWPIN,
> PSWPOUT,
> ...
> NR_VM_EVENT_ITEMS,
> };
>
> enum vm_global_event_item {
> KSWAPD_STEAL = NR_VM_EVENT_ITEMS,
> KSWAPD_INODESTEAL,
> ...
> };
>
> and then in count_vm_event(), check
>
> if (item < NR_VM_EVENT_ITEMS) {
> memcg_add_vm_event(mem, item, count);
> }
>
> I don't think we need to be concerned about reordering the global
> /proc/vmstat to fit this purpose.
>
Hmm, ok. will try that.
Thanks,
-Kame
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