[PATCH] io-controller: implement per group request allocation limitation
guijianfeng at cn.fujitsu.com
Tue Jul 14 00:37:59 PDT 2009
Vivek Goyal wrote:
> On Fri, Jul 10, 2009 at 09:56:21AM +0800, Gui Jianfeng wrote:
>> Hi Vivek,
>> This patch exports a cgroup based per group request limits interface.
>> and removes the global one. Now we can use this interface to perform
>> different request allocation limitation for different groups.
> Thanks Gui. Few points come to mind.
> - You seem to be making this as per cgroup limit on all devices. I guess
> that different devices in the system can have different settings of
> q->nr_requests and hence will probably want different per group limit.
> So we might have to make it per cgroup per device limit.
Yes, per cgroup per device limitation seems more reasonable. I'll see what
i can do.
> - There does not seem to be any checks for making sure that children
> cgroups don't have more request descriptors allocated than parent group.
Do we really need to make it hierarchical? IMHO, maintaining this limitation
for cgroups independently is enough.
> - I am re-thinking that what's the advantage of configuring request
> descriptors also through cgroups. It does bring in additional complexity
> with it and it should justfiy the advantages. Can you think of some?
I'll try, but at least, this feature lets us be able to do more accurate
> Until and unless we can come up with some significant advantages, I will
> prefer to continue to use per group limit through q->nr_group_requests
> interface instead of cgroup. Once things stablize, we can revisit it and
> see how this interface can be improved.
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