* Question in crush_add_tree_bucket_item
@ 2012-04-21 13:29 胡瀚森
2012-04-21 17:47 ` Sage Weil
0 siblings, 1 reply; 2+ messages in thread
From: 胡瀚森 @ 2012-04-21 13:29 UTC (permalink / raw)
To: ceph-devel
Hi, everyone.
While reading crush_remove_tree_bucket_item, I found that removed
items will still occupy its original position in the tree, but set its
weight to 0.
And in crush_add_tree_bucket_item, why don't we reuse these items with
0 weight since I don't see additional data migration if we reuse these
nodes?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Question in crush_add_tree_bucket_item
2012-04-21 13:29 Question in crush_add_tree_bucket_item 胡瀚森
@ 2012-04-21 17:47 ` Sage Weil
0 siblings, 0 replies; 2+ messages in thread
From: Sage Weil @ 2012-04-21 17:47 UTC (permalink / raw)
To: 胡瀚森; +Cc: ceph-devel
On Sat, 21 Apr 2012, wrote:
> Hi, everyone.
>
> While reading crush_remove_tree_bucket_item, I found that removed
> items will still occupy its original position in the tree, but set its
> weight to 0.
Yes.. moving items around can result in shifted data.
> And in crush_add_tree_bucket_item, why don't we reuse these items with
> 0 weight since I don't see additional data migration if we reuse these
> nodes?
Lazy implementation. Ideally we should reuse those slots. Patches
welcome! In most cases, people are probably well-served by the straw
bucket, though, so this may not matter too much.
sage
^ permalink raw reply [flat|nested] 2+ messages in thread
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2012-04-21 13:29 Question in crush_add_tree_bucket_item 胡瀚森
2012-04-21 17:47 ` Sage Weil
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