Re: [patch 0/4] [RFC] Another proportional weight IO controller

[Vivek Goyal <vgoyal@redhat.com>]

On Fri, Nov 21, 2008 at 04:05:33AM +0100, Fabio Checconi wrote:
> > From: Vivek Goyal <vgoyal@redhat.com>
> > Date: Thu, Nov 20, 2008 04:31:55PM -0500
> >
> ...
> > Hi Fabio,
> > 
> > I though will give bfq a try.  I get following when I put my current shell
> > into a newly created cgroup and then try to do "ls".
> > 
> 
> The posted patch cannot work as it is, I'm sorry for that ugly bug.
> Do you still have problems with this one applied?
> 
> ---
> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
> index efb03fc..ed8c597 100644
> --- a/block/bfq-cgroup.c
> +++ b/block/bfq-cgroup.c
> @@ -168,7 +168,7 @@ static void bfq_group_chain_link(struct bfq_data *bfqd, struct cgroup *cgroup,
>  
>  		spin_lock_irqsave(&bgrp->lock, flags);
>  
> -		rcu_assign_pointer(bfqg->bfqd, bfqd);
> +		rcu_assign_pointer(leaf->bfqd, bfqd);
>  		hlist_add_head_rcu(&leaf->group_node, &bgrp->group_data);
>  		hlist_add_head(&leaf->bfqd_node, &bfqd->group_list);

Thanks Fabio. This fix solves the issue for me.

I did a quick testing and I can see the differential service if I create
two cgroups of different priority. How do I map ioprio to shares? I
mean lets say one cgroup has ioprio 4 and other has got ioprio 7, then
what's the respective share(%) of each cgroup?

Thanks
Vivek