On Tuesday, May 21, 2013 02:37:53 PM Tang Chen wrote:
> Hi Rafael,
>
> Please see below.
>
> On 05/04/2013 07:21 PM, Rafael J. Wysocki wrote:
> ......
> > static BLOCKING_NOTIFIER_HEAD(memory_chain);
> > @@ -278,33 +283,64 @@ static int __memory_block_change_state(s
> > {
> > int ret = 0;
> >
> > - if (mem->state != from_state_req) {
> > - ret = -EINVAL;
> > - goto out;
> > - }
> > + if (mem->state != from_state_req)
> > + return -EINVAL;
> >
> > if (to_state == MEM_OFFLINE)
> > mem->state = MEM_GOING_OFFLINE;
> >
> > ret = memory_block_action(mem->start_section_nr, to_state, online_type);
> > -
> > if (ret) {
> > mem->state = from_state_req;
> > - goto out;
> > + } else {
> > + mem->state = to_state;
> > + if (to_state == MEM_ONLINE)
> > + mem->last_online = online_type;
>
> Why do we need to remember last online type ?
>
> And as far as I know, we can obtain which zone a page was in last time it
> was onlined by check page->flags, just like online_pages() does. If we
> use online_kernel or online_movable, the zone boundary will be
> recalculated.
> So we don't need to remember the last online type.
>
> Seeing from your patch, I guess memory_subsys_online() can only handle
> online and offline. So mem->last_online is used to remember what user has
> done through the original way to trigger memory hot-remove, right ? And
> when
> user does it in this new way, it just does the same thing as user does last
> time.
>
> But I still think we don't need to remember it because if finally you call
> online_pages(), it just does the same thing as last time by default.
>
> online_pages()
> {
> ......
> if (online_type == ONLINE_KERNEL ......
>
> if (online_type == ONLINE_MOVABLE......
>
> zone = page_zone(pfn_to_page(pfn));
>
> /* Here, the page will be put into the zone which it belong to last
> time. */
To be honest, it wasn't entirely clear to me that online_pages() would do the
same thing as last time by default. Suppose, for example, that the previous
online_type was ONLINE_MOVABLE. How online_pages() is supposed to know that
it should do the move_pfn_zone_right() if we don't tell it to do that? Or
is that unnecessary, because it's already been done previously?
> ......
> }
>
> I just thought of it. Maybe I missed something in your design. Please tell
> me if I'm wrong.
Well, so what should be passed to __memory_block_change_state() in
memory_subsys_online()? -1?
> Reviewed-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
>
> Thanks. :)
Thanks for your comments,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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