Kame wrote:
> maybe
>
> if (new_pgdat) {
> register_one_node(nid); <-- add sysfs entry of node
> <here>
> }
I am not sure why you suggest this, but perhaps you ar saying that I
don't need to call my new cpuset hook (that tracks node_online_map)
everytime we set a bit here in node_online_map, but only when we set a
bit that wasn't previously set.
Hmmm ... this mm/memory_hotplug.c:add_memory() code seems to have
more code than it needs:
================================================================
int add_memory(int nid, u64 start, u64 size)
{
pg_data_t *pgdat = NULL;
int new_pgdat = 0;
...
if (!node_online(nid)) {
pgdat = hotadd_new_pgdat(nid, start);
if (!pgdat)
return -ENOMEM;
new_pgdat = 1;
...
}
...
/* we online node here. we can't roll back from here. */
node_set_online(nid);
if (new_pgdat) {
ret = register_one_node(nid);
================================================================
It looks like the call to node_set_online() could also be called
only if it wasn't already set, and that the 'new_pgdat' is not
needed as we can just test for pgdat != NULL.
That leads to this code that's a couple lines shorter:
================================================================
int add_memory(int nid, u64 start, u64 size)
{
pg_data_t *pgdat = NULL;
...
if (!node_online(nid)) {
pgdat = hotadd_new_pgdat(nid, start);
if (!pgdat)
return -ENOMEM;
...
}
...
if (pgdat) {
/* we online node here. we can't roll back from here. */
node_set_online(nid);
ret = register_one_node(nid);
================================================================
Is this second code chunk just as good?
I'd still be inclined to add my new cpuset hook to track
node_online_map right after the node_set_online() call, since
that's what changes node_online_map. I don't think I care
whether or not the "sysfs entry of node" is setup or not.
> (When I implements node-hotplug invoked by cpu-hotplug, I'll care cpuset.)
Good - thanks.
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <[email protected]> 1.925.600.0401
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