Re: [PATCH 11/12] blkcg: kill blkio_policy_node

From: Vivek Goyal
Date: Thu Jan 19 2012 - 15:32:33 EST


On Wed, Jan 18, 2012 at 05:11:29PM -0800, Tejun Heo wrote:

[..]
> @@ -1413,14 +1110,10 @@ static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
> spin_lock_irq(&blkcg->lock);
> blkcg->weight = (unsigned int)val;
>
> - hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
> - pn = blkio_policy_search_node(blkcg, blkg->dev,
> - BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
> - if (pn)
> - continue;
> + hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
> + if (blkg->plid == plid && !blkg->conf.weight)
> + blkio_update_group_weight(blkg, blkcg->weight);

Tejun,

Why do we check for blkg->conf.weight=0 here. Even if a group already has
weight and if user has changed the cgroup weight later, that update should
be propogated to all the groups on all the queues.

Where do we assign default cgroup weight to a blkg upon creation? May be at
group create time, we just need to copy blkcg->weight to blkg.conf.weight.

Thanks
Vivek
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