Re: [ckrm-tech] [RFC][PATCH 2/7] UBC: core (structures, API)

From: Kirill Korotaev
Date: Mon Aug 21 2006 - 06:57:02 EST

+ for (p = ub; p != NULL; p = p->parent) {

Seems rather expensive to walk up the tree for every charge. Especially
if the administrator wants a fine degree of resource control and makes a
tall tree. This would be a problem especially when it comes to resources
that require frequent and fast allocation.

in heirarchical accounting you always have to update all the nodes :/
with flat UBC this doesn't introduce significant overhead.

Except that you eventually have to lock ub0. Seems that the cache line
for that spinlock could bounce quite a bit in such a hot path.
do you mean by ub0 host system ub which we call ub0
or you mean a top ub?

Chandra, doesn't Resource Groups avoid walking more than 1 level up the
hierarchy in the "charge" paths?


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