Re: [PATCH] Expose the statistics in blkio.time and blkio.sectors for the root cgroup

[Manuel Benitez <rickyb@google.com>]

Jens,

Please let me know if this patch is/isn't acceptable. Not having the
statistics exposed at the root is a little bit problematic for our
user-level control programs.

-Ricky

On Wed, Mar 24, 2010 at 5:52 PM, Vivek Goyal <vgoyal@redhat.com> wrote:
> On Wed, Mar 24, 2010 at 04:35:56PM -0700, Ricky Benitez wrote:
>> Currently, the io statistics for the root cgroup are maintained, but
>> they are not shown because the device information is not available at
>> the point that the root blkio cgroup is created. This patch updates
>> the device information when the statistics are updated so that the
>> statistics become visible.
>>
>
> Ok, root group is created when request queue is being initialized and
> device information like major/minor number is not available. This is
> not the cleanest solution but can't think of something better right now.
>
> Acked-by: Vivek Goyal <vgoyal@redhat.com>
>
> Thanks
> Vivek
>
>> Signed-off-by: Ricky Benitez <rickyb@google.com>
>> ---
>>  block/cfq-iosched.c |    5 +++++
>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
>> index dee9d93..4a3579a 100644
>> --- a/block/cfq-iosched.c
>> +++ b/block/cfq-iosched.c
>> @@ -947,6 +947,11 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
>>       unsigned int major, minor;
>>
>>       cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
>> +     if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
>> +             sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
>> +             cfqg->blkg.dev = MKDEV(major, minor);
>> +             goto done;
>> +     }
>>       if (cfqg || !create)
>>               goto done;
>>
>> --
>> 1.7.0.1
>