Re: Low overhead patches for the memory cgroup controller (v4)

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Daisuke Nishimura wrote:
> On Mon, 15 Jun 2009 08:30:06 +0530, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>> Daisuke Nishimura wrote:
>>
>>>  	pc->mem_cgroup = mem;
>>>  	smp_wmb();
>>> -	pc->flags = pcg_default_flags[ctype];
>> pc->flags needs to be reset here, otherwise we have the danger the carrying over
>> older bits. I'll merge your changes and test.
>>
> hmm, why ?
> 
> I do in my patch:
> 
> +	switch (ctype) {
> +	case MEM_CGROUP_CHARGE_TYPE_CACHE:
> +	case MEM_CGROUP_CHARGE_TYPE_SHMEM:
> +		SetPageCgroupCache(pc);
> +		SetPageCgroupUsed(pc);
> +		break;
> +	case MEM_CGROUP_CHARGE_TYPE_MAPPED:
> +		ClearPageCgroupCache(pc);
> +		SetPageCgroupUsed(pc);
> +		break;
> +	default:
> +		break;
> +	}
> 

Yes, I did that in the older code, what I was suggesting was just an additional
step to ensure that in the future if we add new flags, we don't end up with a
long list of initializations and clearing or if we forget to clear pc->flags and
reuse the page_cgroup, it might be a problem. My message was confusing, it
should have been resetting the pc->flags will provide protection for any future
addition of flags.

I am testing your patch which is the modified version of v3 with your changes
and have your signed-off-by in it as well as I post v5. Is that OK?

-- 
	Balbir

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>